Hebrews 11:1-2

Now Faith is the assurance (title deed, confirmation) of things hoped for (divinely guaranteed), and the evidence of things, not seen (the conviction of their reality -faith comprehends as fact what cannot be experienced by the physical senses). For by this (kind of) faith the men of old gained (divine approval).

When we believe by faith, we are taking God at His word.  When we take God at His word, this means we are what God says we are, and we can have what God says we can have and do what God says we can do. We believe and don’t argue with God or doubt His word.  We believe!