What does the Bible say about man's works in salvation?

In Titus 1:15-16, Paul draws a clear distinction between true and false religious teachings, highlighting that false religion focuses on man's works as a means of salvation. The gospel, however, centers on Christ’s completed work, signaling that salvation is through faith in Him alone, not through any human effort. For believers, the assurance comes from understanding that Christ's sacrifice was perfect and complete. Therefore, any attempt to add to His work is both unnecessary and insulting to His sacrifice, as He stated, 'It is finished.' Believers are to rest in this finished work rather than labor under the false notion that they must earn salvation through their deeds.