Because Jesus requires our acknowledgement. All glory goes to him in EVERYTHING.If I do good in my life and follow all the principles God allegedly wishes, even if I don't do it in his honor or with belief in him as to why I do those things, why would faith be a decider? Does that seem logical to you?
John 3:3
Truly, truly I say unto you, unless one is born again, he shall not see the kingdom of God.
Luke 13:3
No, I tell you; unless you repent, you will all likewise perish.
Titus 3:5
He saved us not of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit.