One footprint I see is mans ability to reason and to be spiritual as well as physical. I should think that many Jews would also describe its victories against huge odds as footprints too.
Disbelief in God is an admission that man has no soul and is led purely by instinct, habit or conditioning.
I believe in a creator because of events that happened in my life. Have you ever had a voice inside your head tell you that something will happen and within one week it does?
This has happened to me a few times now and usually while I was occupied with something else totally unrelated. it was never about winning lotto numbers unfortunately.
You may try to explain this away but I know what I know and so I will stick with Hashem because he has stuck by me.