Don't try to convince non-believers that gay marriage is wrong

I often get asked, "How do I convince my gay friend who isn't a Christian that gay marriage is wrong?"

You probably won't.

I doubt you'll convince any non-Christian (gay or straight) to impose restrictions on themselves that contradict widely-held cultural wisdom.

Even if this person calls themself a Christian, that doesn't mean Jesus is the Lord of their life. That doesn't mean that they're actually willing to submit to Christ's culturally-inconvenient wisdom.

The better questions to ask are:
Do you believe that a God exists?
Do you believe that God knows what is best for us?
Do you believe that the Bible and the Church are how we know who that God is?

These questions have nothing to do with sexuality, but much more often than not, they will determine how a gay person (or any person, for that matter) will steward their lives.

If someone answers "no" to one or more of those questions, conversation about what the Church or the Bible has to say about sexual stewardship is a waste of time.

Instead, spent your time and energy on these three fundamental questions.