It is the unrepentant (unsaved) whose conscience is seared (1 Timothy 4:2) and cannot be perfected even with rituals/sacrifices, but by recieving daily instruction from The Holy Spirit (the eternal spirt, Hebrews 9:15), our conscience will be purified (provided we are good students). On the cross, as the Lamb of God, Jesus destroyed death, but it is a function of The Spirit that offers a clear conscience (Hebrews 9:14 (baptism is an appeal to God for a clear conscience). "By rejecting conscience, certain persons have made shipwreck of their faith (personal relationship)1 Timothy 1:19 .