Salvation by Works and Salvation by Faith Contrasted
Salvation by works is putting your trust in yourself; that you can make it; that you can pass by your own performance. It is being confident in yourself that you can measure up to God's perfect standard.
Salvation by works is salvation by self.
On the other hand, salvation by faith or reliance in the Savior is the humble acknowledgment that you can't make it; that you could never pass by your own performance. It is being confident in the Savior's work on the cross and of Him being your Substitute who does measure up to God's perfect standard.
Salvation by faith is salvation by a Substitute.
If you are given an offer to pass muster, make the grade, qualify for salvation, through the perfection of a substitute, would you take it? Would you rely on Christ's work for you and of Him as your substitute? Or would you rather be saved by your own performance?
Would you take a perfectly righteous Substitute on your behalf? Or would you take your chances in yourself as you are, confident in your own righteousness before God?
P.S. Salvation by faith plus works won't do. Once you get your imperfect rating involved you will mess it up. Salvation by faith plus works is like agreeing to be graded on both Christ's perfect score along with your imperfect grade. No problem on His side, it's your end that spoils it all.