Question

how can you prove that God is there. who answered this they can become intelligent

Answer 1

There is nothing in the world which can prove the presence of god, do you know why ?
Because god is not a maths solution, god is a belief means if you believe in god then he exists if you aren't then nothing matters to you.

Answer 2

If God exists:

   God does not want to prove his/her existence by having to convince someone (especially atheists). God appears to those who sincerely believe Him and trust Him, at the time when He thinks that they are fit to see Him.

If God does not exist,
   One cannot prove of His existence, obviously.

Coming out of these arguments that result in nothing of consequence, we can say the following. Instead of looking at God as a person up there in the skies overlooking us, look at God as the embodiment of truth, good, altruism, humanity, love, non-violence, helping nature, prosperity etc. 

So God is there in you yourself and in the smiles of innocent small kids. You have to discover yourself that God. Searching outside does not help. One always remains an atheist.
  
  If you ask me, I felt and saw some incidents that did convince me of the existence of God in some form.  But during the daily busy life, I forget that part.

Existence of God cannot be proved by scientific methods that we have learnt. But great scientists have felt the existence and have said too of the existence.