…and Christianity is given here.
The question being: Why is homosexuality forbidden when other restrictions in Leviticus restricts are not?
The scriptural conflict is well documented in the Acts of the Apostles from acts Chapter 10 (Peter and Cornelius) and the initial reaction of the circumcised. (Chapter 11) and the final decision to not force Gentile converts to what would become called Christianity with the Jewish Levitical laws (chapter 15)
Here is the text of the letter that went out:
This is the letter delivered by them: “The apostles and the presbyters, your brothers, to the brothers in Antioch, Syria, and Cilicia of Gentile origin: greetings.
Since we have heard that some of our number (who went out) without any mandate from us have upset you with their teachings and disturbed your peace of mind, we have with one accord decided to choose representatives and to send them to you along with our beloved Barnabas and Paul, who have dedicated their lives to the name of our Lord Jesus Christ. So we are sending Judas and Silas who will also convey this same message by word of mouth:
‘It is the decision of the holy Spirit and of us not to place on you any burden beyond these necessities, namely, to abstain from meat sacrificed to idols, from blood, from meats of strangled animals, and from unlawful marriage. If you keep free of these, you will be doing what is right. Farewell.'” Acts 15:23-29
Important note, the prohibition against “unlawful marriage” applies to heterosexual sexual immorality as well.
To any Christian the story of Peter and Cornelius is very significant since it was the introduction of the faith outside of the Christian Community and the Counsel of Jerusalem was the defining moment where the Christian Faith took the single most critical step to being considered something other than a breakaway Jewish cult. And yet Paul who was leading the drive against forcing Jewish Law on the new gentile converts was no less adamant on sin:
Now the works of the flesh are obvious: immorality, impurity, licentiousness, idolatry, sorcery, hatreds, rivalry, jealousy, outbursts of fury, acts of selfishness, dissensions, factions, occasions of envy, drinking bouts, orgies, and the like. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God. Galatians 5:19-21
Important note: Paul lists a plethora of sins to avoid, from envy to drunkenness, not simply sexual immorality.
It is that basic misunderstanding of the development of Christianity that makes the talking point effective to that half of the culture that is secular or to poorly catechized Christians.