What's wrong with us existing "just because?" I mean, when it comes down to it we are pretty much just a result of natural evolutionary forces, and if not for evolving a better-working brain than most animals, we'd be running around naked trying to kill other animals for food. It's those higher-order brain functions we evolved with which lead us to believe we have some special purpose on this planet.
Christian apologetics is the art of rolling a dog turd in sugar and selling it as a donut.