The short answer is to refer to the natural order. The only way to get the next generation of human beings is by the union of one man and one woman. This is true of both secular and religious people. While we should respect homosexual persons, and that they can choose to live how they wish, we should also understand that same-sex marriage is to impose on the institution of marriage a definition that does not apply. And even if laws are passed that grant the label of marriage to homosexual persons, it is not marriage as commonly understood, Further, there is enough evidence to show that children will be taught about gay sexual behavior as being OK. This is far beyond the teaching requirements of any school, public or religious, since young minds are not yet mature enough, emotionally and intellectually. In other words, they cannot fully comprehend as an adult would. This amounts to indoctrination by force of law.
Here is what the Church tells us:
vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_20030731_homosexual-unions_en.html
No one should be bullied, threatened or physically harmed for being gay, and the same holds true for straights doing the same to other non-homosexual persons. Sadly, some teens, in particular, have this nasty habit of picking on the “fat” kid, or the weakling that is not as physically strong as they are, or the nerds, etc.
You may hear the words hate and bigot, but these words do nothing to further a reasonable discussion.
Peace,
Ed