How do you think we came to know about 'God'?

Well I don’t think anyone has seen God.Then how we came to know about God without observing it?
How we came up with the idea of so very existence of God?
Do you believe in God just because so many other people or your parents or elders do?
Or is it just an assumption by humans accrediting ‘God’ for all the scientifically unexplained phenomena in order to ease ourselves out of all the confusions.