I fell victim to this phenomenon yesterday. Check out my reputation score. People saw that I'm a Christian conservative and proceeded to downvote a bunch of my contributions that have absolutely nothing to do with religion or politics, which previously had zero downvotes.
I like the idea of making downvotes from the profile page not count.
You absolutely don't have to. But when you're a Christian, you love God with all your heart, all your mind, and all your soul; and you love your neighbor as yourself. The result is that you do good works by virtue of doing God's will. Good works are a result of salvation.