Observe the beauty of nature (sunset, waves in the ocean, waterfalls, colorful flowers...), the birth of a child (not to mention the process of how it develops in the womb after conception), the way our bodies work (our brains, our hearts pumping blood, how our eyes are able to focus to see things close and far)...so intricate and complicated yet it all works.
I refuse to believe that our existence is coincidental or accidental. There has to be something bigger than us to have created us. Something powerful, wise and loving. And that is God.
And people don't believe in God because they get stuck on that there is suffering and death. But the Bible has an answer for that and many other things. And it also explains what God proposes to do to fix everything, so that we may live and enjoy life to the fullest extent, which is how it was intended to be in the beginning of human existence.