The Old Testament
The Old Testament prohibits homosexuality (and therefore bisexuality).
“You shall not lie with a male as with a woman; it is an abomination (Leviticus 18:22).”
“If a man lies with a male as with a woman, both of them have committed an abomination;… (Leviticus 20:13).
“But these verses are from the Old Covenant that God made with Moses and the Jewish people. Christians live under the New Covenant and therefore these passages are not binding.”
While much of the Old Covenant is not binding on Christians, it is mistaken to assert that none of it is binding on Christians. What primarily carries forward are moral commandments. Nine out of the Ten Commandments are repeated in the New Testament. The prohibition against homosexuality is not just repeated in the New Testament but is even more clear. And both chapters 18 and 20 in Leviticus are clear that God is not only finds homosexuality sinful for Jews but Gentiles as well.
“Do not make yourselves unclean by any of these things, for by all these the nations I am driving out before you have become unclean, and the land became unclean, so that I punished its iniquity, and the land vomited out its inhabitants. But you shall keep my statutes and my rules and do none of these abominations, either the native or the stranger who sojourns among you (for the people of the land, who were before you, did all of these abominations, so that the land became unclean), lest the land vomit you out when you make it unclean, as it vomited out the nation that was before you. For everyone who does any of these abominations, the persons who do them shall be cut off from among their people. So keep my charge never to practice any of these abominable customs that were practiced before you, and never to make yourselves unclean by them: I am the Lord your God (Leviticus 18:2-30).”
“You shall therefore keep all my statutes and all my rules and do them, that the land where I am bringing you to live may not vomit you out. And you shall not walk in the customs of the nation that I am driving out before you, for they did all these things, and therefore I detested them (Leviticus 20:22-23).”
So God judged the Canaanites sexual sins to be so serious He had them driven out of their land. Leviticus 18:26 also mentions that both native (Jews) and strangers (Gentiles) were not to engage in the sexual sins listed in the chapter.
“But these passages are referencing abusive homosexuality, such as between men and boys. That was common then and must be what Moses had in mind.”
Both passages speak of adults, men and women. To say otherwise is to read into the text and not what it actually states. There is simply no basis for such an interpretation.
“These passages only speak of male homosexuality. Therefore, lesbianism must be permissible.”
There are no biblical or extra-biblical historical records of religious Jews approving of lesbian relationships. But the New Testament does directly address lesbianism in Romans 1.
The New Testament
“For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature; 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 themselves the due penalty for their error (Romans 1:26-27).”
“Again, this is addressing abusive homosexuality, such as between men and boys. That was common then and must be what Paul had in mind.”
First, the passage only references adults. Second, is was not common for women to abuse girls. This is further evidence the claim that the Bible means to only reference adult homosexuality with youth is unfounded. Third, notice both homosexual partners are “consumed with passion for one another.” Children are not consumed with passion for their sexual abusers.
“Romans 1:22-25 states that these people became very sinful because of idolatry, worshiping created things instead of God. He then gives them over to their lusts and they delve into their sins, the first listed being homosexuality. So this passage doesn’t even apply to homosexuals worshiping God in Christian churches.”
The teaching of Romans 1 continues into chapter 2:
“We know that the judgment of God rightly falls on those who practice such things. Do you suppose, O man—you who judge those who practice such things and yet do them yourself—that you will escape the judgment of God? Or do you presume on the riches of his kindness and forbearance and patience, not knowing that God’s kindness is meant to lead you to repentance? But because of your hard and impenitent heart you are storing up wrath for yourself on the day of wrath when God’s righteous judgment will be revealed (Romans 2:2-6).”
So some of the Christians in the Roman church were engaging in the sins listed in chapter 1, including homosexuality. Such people “deserve to die” (Romans 1:32), are under God’s judgment (Romans 2:2-3) and wrath (Romans 2:5). The passage applies to both people inside and outside the church.
Romans 2:4 states that God is kind and patience towards people in order to lead them toward repentance. People of all sexuality have to struggle with putting God’s will above their own. But when we do this, the Bible states, “And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God (1 Corinthians 6:11).”