The gospel is a glorious thing in and of itself. God granting intellectual assent via imputing His righteous death allows us to ascertain that. It is a miracle in itself.
I think a problem is some folks aren't very impressed with that miracle on it's own. Maybe because they actually don't believe it. They need a sign in their works because ultimately Christ's death alone seems like quite a gamble. Let's throw some of our works in their before a Holy God. Sweeten the pot if you will.
Mark 8:12 KJV
"And he sighed deeply in his spirit, and saith, Why doth this generation seek after a sign? verily I say unto you, There shall no sign be given unto this generation."
Analogy for you imperfect as it is.
I tell you, some folks are mighty confident in their card playing and think it's gonna avail them in the end. We all have the dead man's hand but Christ is our Ace in the hole.
The LORD actually shown us His cards in an analogous sense through faith. He has the "royal flush" and we may as well fold our dead man's cards of "righteousness". Those, in presumption, keep their hand to the end, it's not going to go well for them.
Matthew 7:21-23 KJV
Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
What is our work?
John 6:29
Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent.
When God causes us to believe the gospel, we believe on him whom he hath sent and the glorious work of His person. This is a work of the Spirit. Being born again, regenerated, given a heart of flesh. Yes, ALL these things!
The Matthew 7 crowd probably had what they surmised were "works of obedience". Far from it. The LORD knew them not. Remember Christ is the end of the law for righteousness. The Scriptures say it so I tend to believe them. May God give light.
Romans 10:14 KJV
For Christ is the end of the law for righteousness to everyone who believes.