We know God exists because of creation.
If you go to an art gallery and look at a great painting, you know that it didn’t paint itself. If you find a digital watch on a beach you know that all its complex parts didn’t just form themselves and then put themselves together in perfect working order. And yet the very simplist forms of life are mind blowingly more complex than a digital watch.
And the brush strokes of nature are infinitely more intricate than any work of Picasso. The Bible says that “the heavens declare the glory of God.” True! In fact you really have to want to believe that there isn’t a God to not see His finger prints all over creation!