Why do we even need to consider there is a God ? Because, everything we see around has a purpose from the micro-organisms to the cosmos, and that does not happen by chance..
[Qur'an 38:27] And We did not create the heavens and the earth and that between them
This is the great designer argument and it is false.
If particle 'a' collides with particle 'b' certain consequences follow. But, in an infinite universe, that collision is precisely a matter of chance. It is the very definition of chance. Particle 'a' may just have easily collided with particle 'c' and things would be completely different. Things are as they are, and not as one of the other infinite possibilities, because of that chance collision.