It’s because he says things like this:
“The Lord created us in His image and likeness, and we are the image of the Lord, and He does good and all of us have this commandment at heart: do good and do not do evil. All of us. ‘But, Father, this is not Catholic! He cannot do good.’ Yes, he can. He must. Not can: must! Because he has this commandment within him. Instead, this ‘closing off’ that imagines that those outside, everyone, cannot do good is a wall that leads to war and also to what some people throughout history have conceived of: killing in the name of God. That we can kill in the name of God. And that, simply, is blasphemy. To say that you can kill in the name of God is blasphemy.”
“Instead,” the Pope continued, “the Lord has created us in His image and likeness, and has given us this commandment in the depths of our heart: do good and do not do evil”:
“The Lord has redeemed all of us, all of us, with the Blood of Christ: all of us, not just Catholics. Everyone! ‘Father, the atheists?’ Even the atheists. Everyone! And this Blood makes us children of God of the first class! We are created children in the likeness of God and the Blood of Christ has redeemed us all! And we all have a duty to do good. And this commandment for everyone to do good, I think, is a beautiful path towards peace. If we, each doing our own part, if we do good to others, if we meet there, doing good, and we go slowly, gently, little by little, we will make that culture of encounter: we need that so much. We must meet one another doing good. ‘But I don’t believe, Father, I am an atheist!’ But do good: we will meet one another there.”
The notion that doing good is worth doing no matter what your religion, or lack of religion…yeah. I can get behind something like that. And while this sort of sentiment is pretty commonplace among most people in the Western World, having a pope say it really helps. It’s less ground-breaking than it would have been about thirty years ago, but I’ll take what I can get, and I’ll never push aside a potential ally.