Wa alaikum assalam
If belief in God was only a product of pure scripting, then it would be arguable, that the first human being would have had no knowledge of the existence of a Supreme Creator and his subsequent generations would follow suit in a like manner and there would be no expectation of an intelligent architect to the Universe today.
I trust that you can see how preposterous such a suggestion as that intimated by your atheist friend arguably would be.
Furthermore, there are many humans who have had little / no scripting from their parents (who themselves are disbelievers / agnostics), but have come to the conclusion on their own volition, of the certainty of an Almighty God.
It is also not unheard of that obscure tribes throughout history have had some sort of belief in a higher being / higher beings of sorts (whatever that may be) to explain how the world around them has come into existence including themselves.
The need to believe in a greater existence appears to be innate to the human soul. Verse 7:172 may throw some light on the reason why.
From a purely Quranic perspective however, God ultimately guides whom He wills in the manner He deems appropriate.
I hope this helps, God willing.
Regards,
Joseph