Well, the list of acts we today consider illegal or immoral that Jesus never mentioned is long indeed. "Arguments from silence" are logically unsupportable and inherently deficient. Jesus never talked about whether democracy was superior to monarchy, either. He never talked about whether interest should be charged on loans nor what rate would be usurious. So to say, "Jesus never said homosexuality is unacceptable" is not a serious argument.
Nor is it a true one. There are multiple answers rebutting the claim. One was explained by Vanderbilt Prof. Amy-Jill Levine, a world-class New Testament scholar (and a supporter of the pro-homosexual agenda). She explained in class one day that in both testaments, Jewish prophets spoke to issues that did not accord to obedience to the Law and didn't spend time mentioning popular conduct or attitudes that did accord with the Law. The Law, she said, was clear that homosexual acts were forbidden; Jesus's silence on the topic simply means that the first-century Judeans were not in defiance of the Law on the matter. (That is not to say that there was no one committing homosexual acts then, just that there was popular understanding and strong social mores that the acts were forbidden by the Law.)
When Jesus did speak to sexual relations between persons, it was in such a manner that excluded homosexual acts from permissibility.
Porneia is the word used in the Gospels in which Jesus explained how a husband and wife were permitted to divorce. It used to be translated simply as "adultery," but porneia actually encompasses a broader range of sexual immorality. For example, Paul used the word in 1 Cor. 5 to refer to incest. In non-biblical Greek usage, porneia was used by Greek authors to refer to a wide range of sexual conduct of both heterosexual and homosexual kind, often referring to pagan temple prostitution. But porneia definitely was used to refer to homosexual acts, though not only them.
It simply is not credible that Jesus, a faithful first-century Jew and expert on Jewish Law, would have used the word in a way that excluded homosexual acts, or that his teaching on marriage (the context in which he spoke about divorce) indicated anything but exclusion of same-sex "marriage." Example, Matthew 19:
3 Some Pharisees came to him to test him. They asked, “Is it lawful for a man to divorce his wife for any and every reason?”Jesus very clearly defined marriage solely as between a man and a woman. There is no wiggle room in his meaning. The idea that same-sex "marriage" could credibly be included in how Jesus spoke about marriage in this or other passages simply cannot be sustained. The use of porneia shows definitively that homosexual acts were proscribed by Jesus, though illicit heterosexual acts were as well.
4 “Haven’t you read,” he replied, “that at the beginning the Creator ‘made them male and female,’5 and said, ‘For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’? 6 So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”
7 “Why then,” they asked, “did Moses command that a man give his wife a certificate of divorce and send her away?”
8 Jesus replied, “Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. 9 I tell you that anyone who divorces his wife, except for sexual immorality [porneia], and marries another woman commits adultery.”
To Jesus, sexual relations were licit only between a man and a woman who were married to one another, and no other sort of marriage was even imagined, much less implicitly endorsed.