Existence is not logical.
If we were designed or created, who made the designer?
If the designer was not created or designed, then his existence requires neither.
If a designer is always required for something to exist, then you're stuck in an infinite regression. A god must have made the god that created God and so on and so forth...
But if you think God doesn't require a creator, then you must believe that something complex can exist without a designer or "painter".
So why should imperfect humans require a designer if a perfect being doesn't?
If anything, it makes more sense that our flawed diseased world sprang into existence through impersonal natural processes than to think our flawed diseased world was the product of a flawless almighty deity.