Well, you can't convert a Baptist to a Catholic, or whatever religion you want to compare. It may be possible to convert somebody that thinks they belong in the herd instead of being a protector of the herd.
I'll continue to quietly bring them around without just dismissing them. If I can, it adds numbers to the shepherds. More shepherds, more safety.
Schooling is what it'll take if we don't want to alienate all the non owners. Some I've educated still don't own any firearms, but they don't run out in hysteria voting to ban them either.