This information grants us enough for obedience. It is clear how God designed sexuality and God has forbidden us from misuse. Though this does not directly address the question why, which was my friend's question,
I can’t see why God would have a problem with homosexuality, assuming that is was ‘good’ homosexuality. We have many, many examples of ‘bad’ heterosexuality. If we take all of what we say a monogamous, loving, ‘Godly’, heterosexual marriage should be and call that a ‘good’ relationship then I can’t see any difference if you just slotted in the word homosexual instead of heterosexual.What I wish to do here is consider why this might be the case. A knife may not be as effective as a screwdriver but is is not immoral to use it as one.
We need to remember that we are created and God is eternal; our perspective is often anthrocentric but the universe is actually Christocentric. The Godhead is eternal and everything derives from him. As such material things are often reflections of eternal things. Jesus is the son of God but this is not a biological relationship. He did not become the son of God because he was born of Mary via the Holy Spirit, he is the son of God by virtue of his relationship to the Father, of which human sonship is a reflection. Humans are made in the image of God (Gen 1:26).
I bow my knees before the Father, from whom every family [fatherhood] in heaven and on earth is named. (Ephesians 3:15)This may mean that God names, that is defines, family/ fatherhood; or possibly that family/ fatherhood derives its name from who the Father is. Regardless of which is intended here it is clear that earthly fathers are representative of the Father (cf. Mat 7:11; Heb 12:7).
Reproduction does not require 2 genders, some species reproduce asexually and some plants have both male and female components within a single organism. Humans are in the image of God and have 2 distinct genders so it is worth considering if there is a reason for this. Are the sexes representative in some way? Paul addresses this question.
“Therefore a man shall leave his father and mother and hold fast to his wife, and the two shall become one flesh.” This mystery is profound, and I am saying that it refers to Christ and the church. (Ephesians 5:31-32)When God decided to create man it was his intention to create relationship. Humans were to know and be in relationship with God. This relationship between people as a group and God is the primary reason for creation.
Jesus said to him, "You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself." (Matthew 22:37-38)The most important command for all mankind is to love God. Our relationship to God is also primary over our other relationships between each other and this includes marriage. The vertical precedes the horizontal.
So we are created from the beginning to love God. This relationship between those who love God (the church) and God is primary, and of which marriage is a reflection. Marriage between men and women is an image of the relationship between God and man. In the same way that fathers are an image of the true Father, whom they are to imitate; so marriages are an image of the true Marriage between Christ and the church. God created the 2 sexes (at least in part) so we would have an image of our relationship with Jesus. This explains the use of the term bridegroom as applied to Jesus and bride to his followers (Joh 3:29); and this is not just an analogy (Rev 19:7; 21:2; 22:17).
We live in a fallen world, one where we have many marred reflections of Christ and his bride. God even allowed divorce in situations where continuing a marriage is worse than it ending; though that is not what God intended (Mat 19:8). As my friend has noted there are many examples of bad heterosexuality including both bad marriages and refusal to marry. Nevertheless, such bad heterosexuality is a poor reflection of Christ and the church whereas homosexuality, whether so-called "good" or "bad," is not a reflection of Christ and the church at all. Homosexual relationships at their core misrepresent our relationship with God. Created beings cannot define the world from their perspective, they must accept the intents of their creator. If the creation of the 2 sexes (male and female) and marriage between them was invented by God in order to reflect the relationship between mankind and God then we must accept his design and submit to it. Refusal to do so is an affront to God and rebellion against his plans.
Part 1. Part 2. Part 3. Part 4.