WHAT DO THE SCRIPTURES REVEAL ABOUT HOMOSEXUALITY?

All of us are called to receive eternal life by deepening our relationship with God. This is our purpose in life, to love Him and make Him loved. In order for us to truly love our Lord, we need to be faithful to His Divine will and avoid sins. Obedience is an act of love. We obey because we love, and we trust that the One whom we obey desires the best for us. This is because God's will is always good, pleasing, and perfect.

Part of His will is that marriage is only between a man and a woman. As such, any sexual activity should only be done within marriage between a man and a woman. Although attraction is not a sin in and of itself, what a person does with attraction is what constitutes a sin. One way to know God's will is by looking at the Scriptures, and we can see in Genesis the institution of marriage.

Genesis 1:27-28

27 So God created man in His own image, in the image of God He created him; male and female he created them. 28 And God blessed them, and God said to them, “Be fruitful and multiply, and fill the earth and subdue it; and have dominion over the fish of the sea and over the birds of the air and over every living thing that moves upon the earth.”

God instituted that marriage is between a man and a woman, and this is already seen during the creation. Adam and Eve were the first married couple. There are two inseparable purposes of marriage - the unitive and procreative. These two purposes must go together while remaining distinct. Any violation from either purpose can be considered a grave sin. Not only that we have an affirmation that marriage is exclusive to man and woman, but there is also an explicit condemnation in Leviticus. 

Leviticus 18:22

22 You shall not lie with a male as with a woman; it is an abomination. 

However, some supporters of homosexuality defend their view by saying that the commandments in the Old Testament are no longer binding just as prohibition of pork and circumcision of male babies are no longer required. What they have not acknowledged is that only the ceremonial laws are no longer binding, but the moral laws will always be required for all of us. This is why we continue to see the Catholic position on marriage even in New Testament where people are no longer required to follow ceremonial laws. 

Matthew 19:4-5

4 He answered, “Have you not read that he who made them from the beginning made them male and female, 5 and said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one’?

Romans 1:26-27

26 For this reason God gave them up to dishonorable passions. Their women exchanged natural relations for unnatural, 27 and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in their own persons the due penalty for their error.

The fact that Jesus intends the people to be more faithful to the original intention of marriage in Genesis signifies that marriage is only between a man and a woman. In the letter of St. Paul, he clarified that men and women gave up their natural relations for the unnatural. As such, acting on homosexual desires, whether between two men or two women, is not in accordance to the will of God and our human nature given that He designed our sexuality to be ordered towards fruitfulness in procreation. This is also why the Catholic Church teaches that homosexual acts are contrary to the natural law and cannot be approved. Nonetheless, we should still respect people with same-sex attractions by treating them with dignity because all of us are created in the image of God. Rather than mock them and make fun of them, God desires that we pray for everyone, especially people struggling with same-sex attraction. In this way, they may be more open to grace to persevere in following the will of God, especially in practicing chastity. As what the Catechism of the Catholic Church states,

"2359 Homosexual persons are called to chastity. By the virtues of self-mastery that teach them inner freedom, at times by the support of disinterested friendship, by prayer and sacramental grace, they can and should gradually and resolutely approach Christian perfection [1]."

Reference:

[1]http://www.scborromeo.org/ccc/para/2359.htm