This didn’t make much sense to me when I was 15 and in the process of leaving Christianity. It doesn’t make much sense to me today.
But if this theology inspires people to be better than they are, I’m all for it. And if it inspires them to sense of superiority or insularity, then it’s a wrong theology.
As for conversions, my hypothesis is that people who need to convert others are not all that secure in their own belief. A “convert” helps validate their own faith.