Simply put, all sin is an offense against God because it sets itself against God's love for us and turns our hearts away from Him. Mortal sin is a grave violation of God's law and destroys charity in the heart of man. Mortal sin is not capable of being forgiven through any power within the soul itself, a special intervention by God is required (much like the human body which, once it dies, can only be resurrected by God). This is why Catholics have the Sacrament of Reconciliation (penance/confession); so that God can again become sacramentally present and active in our lives. For a sin to be mortal, three conditions must all be met: the object must be a grave matter, it must be committed with full knowledge, and it must be committed with deliberate consent.

Venial sin allows charity to subsist, even though it offends and wounds it. The term "venial" comes from the Latin word venia which means pardon. This term is applied to less than mortal sin because the soul has a vital principle that allows a cure from within (much like a diseased or sick body which fights off the invasion and recovers).

Recommended reading:
Catechism of the Catholic Church, Libreria Editrice Vaticana, 1994, paragraphs 1854-1864.
Hardon, John A., S.J., The Catholic Catechism, Doubleday, New York, NY, 1981, pages 183-185.

Q. What is the unforgivable sin?

Luke 12:10 (see also Matthew 12:32 and Mark 3:29) says:

"And everyone who speaks a word against the Son of Man will be forgiven, but anyone who blasphemes against the Holy Spirit will not be forgiven." (NIV)

Blasphemy against the Holy Spirit is to reject His grace. Not allowing the Holy Spirit to work in our lives is blasphemy: It is saying "I know more than God does about what is right for me" which takes away the principle which makes it possible to ask for forgiveness. This manifests itself in four ways: 1) despair concerning the possibility of salvation; 2) presumption of God's mercy and forgiveness; 3) denial of the truths of faith; and 4) final impenitence and refusal to turn to God. Sins against the Holy Spirit are the most grave because they reject the dignity of the One sent by the Father to sanctify us and restore us to full union with Him. Belief that if anyone fails to be open to the workings of the Holy Spirit in their lives, even once, automatically condemns them to Hell forever is not the teaching of this passage in Holy Scripture. This passage addresses the condition of the soul at the moment of death; prior to that moment, every person has the opportunity to turn to God, have their sins forgiven, and be welcomed home like the prodigal son (Luke 15:11-32)

Recommended reading:
 Catechism of the Catholic Church, Libreria Editrice Vaticana, 1994, paragraph 1864
 Stravinskas, Rev. Peter M. J., Our Sunday Visitor's Catholic Encyclopedia, Our Sunday Visitor, Huntington, IN 46750, 1991, page 481
 To Sin Is To Die, Booklet #49, Catholic Information Service, Knights of Columbus, P.O. Box 1971, New Haven CT 06521, 1967

Q. Is it a mortal sin to miss Mass on Sundays?

The 3rd Commandment tells us to keep the Lord's Day holy. In Old Testament times, God's people stopped working and gathered together for worship on the Sabbath, which was Saturday. However, the early Christians rested and came together to rejoice on Sunday because Jesus, Our Lord and Savior, rose from the dead on Easter Sunday morning. Sunday is not only a day of worship but a day of joy and family closeness.

Now as to whether it is a mortal sin or not. The three criteria for determining if a sin is mortal were described under the question on mortal and venial sin. It is a grave matter to miss Mass on Sunday. If we have full knowledge that it is a sinful matter to violate one of the Ten Commandments because it violates God's law, the second condition is met. If we realize that the 3rd Commandment requires us to gather together to worship and we know that it is a grave sinful matter to violate the Commandments, but the car won't start and there is no other way to get to Mass, the third condition has not been met. If however, we simply miss Mass because there is something else we would rather be doing (like playing golf, going to the beach, etc.) then a deliberate act has taken place and a mortal sin has been committed. It's like saying "I don't love God enough to spend some of my time with Him."

Recommended reading:
 Catechism of the Catholic Church, Libreria Editrice Vaticana, 1994, paragraphs 1857-1861
 "Remember The Sabbath . . . Keep It Holy", Booklet #36, Catholic Information Service, Knights of Columbus, P.O. Box 1971, New Haven CT 06521, 1967

Q. Is masturbation a mortal sin? If it is, why?

First, we must understand that our sexual organs are good and beautiful because they were given to us by God for the most noble purpose of continuing the human race. Genesis 1:27-28 says:

"So God created man in his own image, in the image of God he created him; male and female he created them. God blessed them and said to them. 'Be fruitful and increase in number; fill the earth and subdue it.'" (NIV)

Our sexual organs were given to us by God; his for her and hers for him so that this command can be fulfilled.

Second, the sex act in marriage is also good and beautiful because of its twofold God-given purpose: for the generation of children, and as an expression of true mutual love between the spouses. God performed the initial act of creation when He formed Adam and took the woman from his side. In the sex act in marriage, the couple is complying with God's command and is in essence performing an act of re-creation; with God's help they are creating a new life.

Masturbation is the deliberate stimulation of the sex organ in order to derive sexual pleasure. As such, it is an act of recreation rather than re-creation and is ordered toward self rather than toward God. The 6th Commandment is "You shall not commit adultery" (Exodus 20:14; Deuteronomy 5:18) and this prohibits any sexual activity except with one's lifelong partner in the Sacrament of Matrimony. Even if you are not married, the teaching of the Catholic Church has always been that the 6th Commandment encompasses all sexual activity. After all, Jesus said that the greatest commandment was that you shall "love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength" (Mark 12:30, NIV) and self-centered recreational sexual activity violates this command.

Whether masturbation is a mortal or venial sin depends upon the criteria for a sin to be mortal which were given in the answer to the question on mortal and venial sin. Now that you know that it is a grave sin and why, it is a mortal sin.

Recommended reading:
 Catechism of the Catholic Church, Libreria Editrice Vaticana, 1994, paragraph 2352
 Hardon, John A., S.J., The Catholic Catechism, Doubleday, New York, NY, 1981, pages 354-356
 Drummey, James J.,  C. R. Publications, Norwood, MA 02062, 1995, pages 407-410

Q. If we sin, can we bless ourselves with holy water and take Communion or do we have to go to Confession?

All mortal sins require the sacramental presence of God in our lives to be restored. For this reason, all mortal sins require the Sacrament of Reconciliation (penance/confession) in order to obtain absolution. One must not be in a state of mortal sin and receive the Eucharist because to do so would constitute another mortal sin. In the case of venial sins, blessing oneself with holy water is not sufficient to remove the stain of the sin and receive the Eucharist, but it is a start. A sincere act of contrition and a sincere participation in the Penitential Rite of the Mass will absolve venial sins and the Eucharist can be received.

Recommended reading:
 Stravinskas, Peter M. J., The Catholic Answer Book, Our Sunday Visitor, Huntington, IN, 1990, page 31

Q. Is it a sin to drink alcohol?
Q. Is it a sin to get drunk?

Nowhere in the Bible is the use of alcoholic beverages prohibited. If it were sinful, would Jesus have changed water into wine at Cana (John 2:1-11)? Jesus drank wine and was falsely accused of being a drunkard (Matthew 11:19). The drinking of alcoholic beverages is nothing more than making use of what God has provided and is not a sinful act. In fact, the Bible says

"He causeth the grass to grow for the cattle, and herb for the service of man: that he may bring forth food out of the earth; And wine that maketh glad the heart of man, and oil to make his face to shine, and bread which strengtheneth man's heart." (Psalm 104:14-15, KJV)

"Drink no longer water, but use a little wine for thy stomach's sake and thine often infirmities." (1 Timothy 5:23, KJV)

Notice that Holy Scripture says "a little wine," not copious quantities. Use of any alcoholic beverage to the point of becoming intoxicated is a misuse of God's gift and is a sinful act. Throughout the Bible there is a clear distinction made between the use of alcohol and the abuse of alcohol (Ephesians 5:18 & Proverbs 20:1 for example).

Recommended reading:
 Catechism of the Catholic Church, Libreria Editrice Vaticana, 1994, paragraph 2290
 Mbukanma, Rev. Jude O., Is it in the Bible?, Scripture Keys Ministries Australia, Broadford, Victoria, Australia, 1987, pages 59-66

Q. Is it a sin to gamble?

Matthias was chosen by lot as the apostle to replace Judas Iscariot (Acts 1:26). In Leviticus 16:8, Aaron casts lots to determine which goat is to be sacrificed for the people and which is to be released in the desert. In Joshua 18:10, Joshua casts lots to determine what portion of the promised land each tribe is to receive. Casting lots is a form of gambling. If the Apostles did it and recorded it in Holy Scripture without condemning it, it must not be a sinful act. All this said, any time someone gambles away something to the detriment of their attention to God, to themselves, and to their family, then it becomes a sinful act.

Recommended reading:
Catechism of the Catholic Church,  Libreria Editrice Vaticana, 1994, paragraph 2413

Q. Is it wrong to "shop around" for a priest to let you use birth control?

From the way your question is worded it is obvious that you are aware that contraception is a serious matter and have full knowledge that it is a sinful act, so you are looking for a loophole which will allow you to escape the blame of giving full consent (these are the three criteria for determining mortal sin). There are no loopholes. Any sinful act is always a sinful act, even if you have "permission" to do it. No priest (or Bishop) can legitimately give "permission" to engage in any sinful act.

Q. Is it a mortal sin to receive Communion without believing that it is truly the body, blood, soul and divinity of Christ?

As adopted by the National Conference of Catholic Bishops and printed in every missalette:

"Catholics fully participate in the celebration of the Eucharist when they receive Holy Communion in fulfillment of Christ's command to eat His Body and drink His Blood. In order to be properly disposed to receive Communion, communicants should not be conscious of grave sin, have fasted for one hour, and seek to live in charity and love with their neighbors. Persons conscious of grave sin must first be reconciled with God and the Church through the sacrament of Penance. A frequent reception of the sacrament of Penance is encouraged for all."

The Catholic belief is that Holy Communion is in fact the body, blood, soul and divinity of our Lord Jesus Christ. This belief will be more thoroughly discussed in the chapter on the Sacrament of the Eucharist. As to whether receiving Holy Communion without believing this, we look to what Saint Paul says as he writes to us in 1 Corinthians 11:23-29:

"For I received from the Lord what I also passed on to you: The Lord Jesus, on the night he was betrayed, took bread, and when he had given thanks, he broke it and said, 'This is my body, which is for you; do this in remembrance of me.' In the same way, after supper he took the cup, saying, 'This cup is the new covenant in my blood; do this, whenever you drink it, in remembrance of me.' For whenever you eat this bread and drink this cup, you proclaim the Lord's death until he comes. Therefore, whoever eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of sinning against the body and blood of the Lord. A man ought to examine himself before he eats of the bread and drinks of the cup. For anyone who eats and drinks without recognizing the body of the Lord eats and drinks judgement on himself." (NIV) [emphasis added]

"For I have received of the Lord that which also I delivered unto you, That the Lord Jesus the same night in which he was betrayed took bread: And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: do this in remembrance of me. After the same manner also he took the cup when he had supped, saying, This cup is the new testament in my blood: this do ye, as oft as ye drink it, in remembrance of me. For as often as ye eat this bread and drink this cup ye do show the Lord's death till he come. Wherefor whosoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of the body and blood of the Lord. But let a man examine himself, and so let him eat of that bread, and drink of that cup. For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord's body." (KJV) [emphasis added]