Twice in Paul’s epistles he refers to “dead works”. In Hebrews 6:1 he writes about “repentance from dead works”, while in Hebrews 9:14 he declares that the blood of Christ avails to “purge the conscience from dead works to serve the living God”.
Mark well, these references are not to wicked works but to dead works. These “dead works” are the so-called “good works” (whether moral or ceremonial) which men did — and still do — to make themselves acceptable to God. They are “dead” because they are not the product of regeneration or spiritual life, but the mere attempt on the part of unregenerate sinners to justify themselves before God.
Paul himself, once zealously religious, but wholly unsaved, had to repudiate his “dead works” and count them “loss” to find salvation in Christ, through whom alone he could produce good works which God could accept. (See Philippians 3:4-9).
This is why he later declared by divine inspiration: “For by grace are ye saved, through faith; and that not of yourselves; it is the gift of God: Not of works, lest any man should boast, for we are His workmanship, created in Christ Jesus unto good works…” (Eph.2:8-10).
“Dead works” are not only unacceptable to God, but an evil substitute for the faith He desires, “for without faith it is impossible to please God” (Heb.11:6). But “he that believeth on the Son of God hath life” and this life is bound to bear fruit— the good works with which God is truly pleased.
The difference between the “good works” of the unregenerate man and the “good works” of a true believer, then, is that the former are “dead works” while the latter are the precious fruit of life possessed.
No man can please God while he denies the truth of His Word or rejects His Son, so graciously given to die on the cross as our Saviour:
“The Father loveth the Son, and hath given all things into His hands. He that believeth on the Son hath everlasting life. And he that believeth not the Son shall not see life; but the wrath of God abideth on him” (John 3:35,36). source