Not bad advice from an atheist is it? Now we don't normally use the word 'proselytize' because, frankly, it sounds, well, odd. "I don't want to proselytize my friends, I like my friends!" (With a nod to Tommy Smothers, if you remember him.) We talk about being missional, or sharing our faith. And we do it for the reason that Penn talks about, but let me say it in kind of a more positive way: How much would we have to love someone to want to rescue them from dying? (Hmm, how much did God love us to do just that?)
See, we aren't missional because it's a way of getting on God's good side, that it earns us points we need to make sure we get into heaven. It's not about putting notches on the belt of faith I wear (like the bat-belt) that shows how good of a Christian I am. It's not even really about responsibility. We want to be missional because there are people in our lives that we genuinely care about, people that we love. And if we love them, and we really believe that they are in danger, we are going to lovingly try to help them see that danger and the way out of it. If we just see it as our duty to tell others about Jesus, then all of our relationships are tinged with ulterior motives, and we discard relationships once our "duty" is done. But if it's about love, then it's more about wanting the best for our friends or family, and an ongoing love for them regardless of how they respond.
I think it's pretty cool that Penn could have that perspective. He really gets it, much better than we as Christians do most of the time. Balaam's ass strikes again! (Obscure Old Testament reference alert, see Numbers 22:21-33 if that intrigues you.)