For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Be Betz
Being that people have died from getting cancer of the rectum, due to being active in anal sex, proves to me it is that which God has commanded against.
Holly Bodine
But people have died plenty from diseases contracted via male/female penis in vagina sex, too. So JUST having negative health outcomes of anal sex cannot be the only rationale that God is commanding against it (in a male/female, marital & consensual fashion).
Kilian Kean
James 4:17 "Therefore, to him who knows to do good and does not do it, to him it is sin."
2 Peter 2:21 "For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them."
If you are convicted about a certain practice, such as eating meat, listening to music that does not glorify or honor God, wearing certain clothes that are provocative, looking out the corner of your eye to lust, spending money on things you know you should not, trading in the stock market, eating too much, or the manner of marriage relations you have in the bedroom, to you it is sin.
Romans 14:19-23 "Therefore let us pursue the things which make for peace and the things by which one may edify another. Do not destroy the work of God for the sake of food. All things indeed are pure, but it is evil for the man who eats with offense. It is good neither to eat meat nor drink wine nor do anything by which your brother stumbles or is offended or is made weak. Do you have faith? Have it to yourself before God. Happy is he who does not condemn himself in what he approves. But he who doubts is condemned if he eats, because he does not eat from faith; for whatever is not from faith is sin."
If the Holy Spirit is speaking to you about something and you ignore him, you are being disobedient. Jesus was even more explicit on this subject. What is going on in your heart?
Matthew 5:28-30 "“But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart. If your right eye causes you to sin, pluck it out and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell. And if your right hand causes you to sin, cut it off and cast it from you; for it is more profitable for you that one of your members perish, than for your whole body to be cast into hell."
However, this is a decision that is between "God, the Husband & the Wife."
Hebrews 13:4 "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge."
Jennifer Rothnie
Consensual sodomy (male/male and male/female) is mentioned in Rom 1:24-27. It was a problem because people were turning from marriage with its responsibilities to the self-fulfillment of lust and depravity with others. Sodomy is a form of fornication.
[Often Rom 1:26 is interpreted as meaning lesbians, since in English it looks like a parallel with 'men committing shameful acts with other men'.
However, in Greek it is much clearer. The women were exchanging the natural function (vaginal sex) for that which lies beside the natural function (anal intercourse). The word para (near, from beside, vicinity of, etc) is used, highlighting the physical proximity. Paul was being as explicit as he could without being crude.]
However, in context of the passage, these people were deliberately turning away from God's design in order to engage in lust and avoid having children.
It is unclear if this act is considered shameful for married, as eros/lust is one part of marriage (Song of Solomon).
As such, to err on the side of liberty, for those who are married to each other it is likely a matter of conscience and personal conviction. It can be said safely that scripture does not advocate it, however, and that medically it is not healthy [anal intercourse can easily lead to tearing, infection, loss of bowel control, etc].
Ben Jones
Someone mentioned that oral sex is sodomy. However I believe oral sex is mentioned in Song of Songs 2: 3 "As the apple tree among the trees of the wood, so is my beloved among the sons. I sat down under his shadow with great delight, and his fruit was sweet to my taste." 4:16 "Awake, O north wind; and come, thou south; blow upon my garden, that the spices thereof may flow out. Let my beloved come into his garden, and eat his pleasant fruits."