I had a few reasons for doing this: preaching from the outside isn't necessarily helpful; there is a heterosexual majority, so it applies to more people; and, actually, what the Bible says about homosexuality to those who are not is a lot more obvious than its message to those who are (sorry, horrible sentence/clause structure there ... made worse by this bracketed section ;) ).
But ... there is real confusion about what the Bible does and doesn't say, and there is a lot of propaganda by various interest groups. So, with a view to providing information for people to make their own choices:-
I'll start by saying that the standard passages quoted on the subject (the ones I looked at last time, from Leviticus, 1 Corinthians and Romans) are not a great deal of use really. The reason is that their application is seriously ambiguous: Leviticus could easily be about one heterosexual man using another in situations where there are no available women (looking after herds, on patrol, whatever); Romans is most likely about the sexual licentiousness and corruption encouraged by Nero and his predecessors (Roman orgies and all that); and 1 Corinthians' malakoi and arsenokoitai are so uncertain in meaning as to be mirrors in which commentators can see their own prejudices reflected back.
I've been trying to research the 1 Cor. terms above in my big book of Greek words and there is surprisingly little there. It seems that malakoi can mean soft things, or weak things or people, or sick people, or people being punished by God. Arsenokoitai doesn't seem to be a proper Greek word at all, but a compound -apparently created created by Paul himself - of arsen (male) and koite (bed). Except that in the Septuagint (the Greek translation of the Old Testament which Paul appears to have used) 'bed' can just mean a place to sleep, or it can mean 'marriage bed', or an animal's den, or a sheepfold, or a sick bed, or ejaculation, or a prostitute's bed, or an idol's shrine - you can maybe start to see why translating a Biblical text is as much art as science. There is one of Paul's lists in Romans 13:13 which explicitly links koite with aselgia, gluttony and sexual excess - as in Roman orgies (again).
A long, geeky paragraph just to say that this particular passage is no help in discerning God's view of homosexuality.
The other passage often quoted is from Genesis 2:
That is why a man leaves his father and mother and is united to his wife, and they become one flesh.Jesus quoted this in the context of marriage (and divorce) whilst Paul quoted it in the context of prostitution (probably cultic, temple prostitutes).
The passage is often used in the argument about gay marriage to say that marriage can only be between a man and a woman, but that requires some extra assumptions. The main assumption needed is that the Bible says everything that is good, so anything not mentioned in the Bible is evil. There are groups who never ride in cars, or wear artificial fibres, or eat non-Mediterranean foods, but they are few ... and, of course, they also don't read Internet blogs or comment on social media or write in newspapers. For most of us, a better approach is to start from what the Bible says and to apply it to the modern world, by extrapolation, analogy, and the application of basic principles - like loving your neighbour, or being faithful to God.
The immediate Biblical context for the quote is earlier in Genesis 2 where God says:
"It is not good for the man to be alone."So you have a choice with Genesis 2. You can say that is just about God giving women to men because mankind is better in relationship than alone. Or you can say that people are meant to function in relationship and in community, so God gives us the marriage relationship as a special form of unity, as illustrated by the (most common) example of a man and a woman.
There is nothing in Genesis 2 to say that marriage must only apply to heterosexual marriage, but there is equally nothing to say that it definitely does also apply to homosexual one too. Read, think, pray, and choose ... and take responsibility for your choice.
A passage about marriage which churches rarely seem to take seriously is in 1 Corinthians:
To the unmarried and the widows I say that it is good for them to remain single as I am.There is an argument that same-sex relationships must be chaste, whilst opposite-sex relationships can culminate in marriage. That is a really Pharisaic loading of burdens onto others by those who are not prepared to carry them themselves, it seems to me. Nevertheless, chastity is a perfectly honourable lifestyle for those with same-sex sexual attraction; just as it is an honourable lifestyle for those with opposite-sex sexual attraction.
But Paul continues that for those who cannot live with this, then it is "better to marry than to burn with passion". It is possible to argue that this only applies to those attracted to the opposite sex, but it is a more natural argument that it applies to all who would otherwise be tempted to promiscuity and extra-marital sex.
Which brings us to idolatry and 'fornication', a word used in old Bible versions to translate porneia, which literally means prostitution or using prostitutes. As used by Jesus and Paul in the New Testament it has particular reference to Hosea's wife, thus to extreme unfaithfulness and to idolatry. Modern translations usually go for the meaningless cop-out of 'sexual immorality'. In the second half of chapter 6 of 1 Corinthians you get:
The body is not meant for sexual immorality but for the Lord, and the Lord for the body. By his power God raised the Lord from the dead, and he will raise us also. Do you not know that your bodies are members of Christ himself? Shall I then take the members of Christ and unite them with a prostitute? Never! Do you not know that he who unites himself with a prostitute is one with her in body? For it is said, ‘The two will become one flesh.’ But whoever is united with the Lord is one with him in spirit.From later context it seems Paul is talking about Temple prostitutes here - ie idolatrous sex.
For me, this is the key point about any form of sexual relationship for a Christian, straight or gay: is it idolatrous, or is it in the context of a faithful walk with God?
There are people for whom that means a life of chastity, and there are people for whom it is married life, or at least the closest equivalent to marriage allowed by law in their locality. Faithfulness and community are key elements for most of us, whether married or single.