Christless religion, of whatever kind, says that we earn God's eternal approval by doing well.  But that is not the gospel of Jesus.  Paul explains by using the metaphor of wages - we earn what is agreed, we get what we deserve.  If we insist on earning divine payment for our good works, we will also deserve our punishment for everything bad.  That is no way to find peace with God.

Circumcision was a mark of faith to the Jews.  It said, ‘I belong to God because I belong to His people’.  However, the Jews thought so much about the sign that they forgot what it meant!  Abraham knew that he belonged to God before he was circumcised, because he believed what God had said.  Eventually he was circumcised because God commanded it and, because he believed what God said, he obeyed (James 2:18-24).

Promises are good, but only if they can be fulfilled.  That is the problem with so much commercial trading: orders not completed, goods not perfect, money not paid on time.  But when God makes a promise, He keeps it. And often He arranges things so that it seems that even God could not do anything - and then He does!

Believers in Jesus are sometimes accused of 'blind faith'.  It is intended as an insult, meaning that 'you cannot see the problems, you cannot understand the issues, so you just believe without evidence ... your so-called-faith is therefore an excuse for not thinking'.  But that is not Biblical faith.  Real faith is realistic.  It fully sees the problems but refuses to allow the difficulties to overcome the confidence that God can do anything; and that He will always keep His promises.