In a time of utter godlessness and moral collapse, Enoch walked with God.  That takes real faith!

Abel offered a better sacrifice than Cain.  But what made Abel's sacrifice acceptable to God?  It was a token of Abel's faith - his conviction that unseen things are real - and his hope in a Saviour still to come.

What is faith?  Believing things with no evidence?   Claiming things from God that He's never promised?  No, faith means living with the assurance that unseen things are real, and that future things are certain.