For me I grew up as a christian and was taught to have faith but as a young person it is a bit difficult to have faith in something you cannot see. Now as an adult my "proof" in God is knowing that he is with me during difficult or traumatic times and he was the one who carried me through. For example with the death of my parents and especially the death of my son. I know that if it wasn't for God I wouldn't have come out with the strength that I have now. There are many more examples I could list, may pop back in later.

Regards,
Dianne