Is it in the UK's interests to leave the EU? It depends on your values. The answer can't be read off of GDP statistics under various scenarios or some measures of global influence.
Give other Christians permission to be different from you. You're not the only Christ-follower in the world, and neither are you the most committed. Your way of loving Jesus is neither the only way for the best. If you don't know that, your Christian world is way too small.