God is the right person to be the ultimate judge of who's acceptable to Him. 

Therefore, we can have hope in Him and Him alone

Our moral code is flawed, it can not compare to God, the creator. 

And so Paul is reminding us that the Gospel is a realistic hope, a hope that was promised, and through the Son of God, Jesus Christ, we have a solution to all of our mess, all our flaws and to where we fall short.