The “wages of sin” are humankind’s due penalty for sins against God. If not for God’s free gift of salvation through His Son, all human beings would be eternally separated from God, but through faith in Christ, we can made right with God for all eternity.
Romans 6:23 reads, "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord." Those who do not place their faith in Jesus Christ will receive the wages of sin. "The wages" refers to a payment. Workers receive a wage or payment for their work. For example, James wrote of "the wages of the laborers who mowed your fields" (James 5:4). First Corinthians 3:8 teaches, "each will receive his wages according to his labor."
Those whose "work" is sin will receive a payment of spiritual death, which is ultimately eternal separation from God in hell. But the second part of Romans 6:23 immediately includes an answer to this problem: Faith in Jesus Christ as Lord, which is the gift of eternal life. This gift is not earned through human effort (Ephesians 2:8-9) but freely given through God's grace because of what Jesus did on the cross, dying as a substitute for our sin. Those who place their faith in Christ will be in God’s presence for eternity (1 Thessalonians 4:17).
After we have put our faith in Christ, it is still possible to experience the symptoms of spiritual death even though we have eternal security. However, when we live out of our old natures rather than out of our new natures (2 Corinthians 5:17), we experience separation from God. The vitality of our relationship with Him is damaged. Thankfully, this relationship can be restored if we confess our sins and turn back to God (1 John 1:9). We may still experience the natural consequences of our sins, but our fellowship with God can be restored.
How can we avoid the "wages of sin" and escape the spiritual death Romans 6:23 mentions? The answer is found in the second half of verse 23. In contrast with death, the gift of God is eternal life in Christ Jesus. The verse is contrasting spiritual death with eternal life.
First, we must place our faith in Christ. Only He can save us (John 14:6). Then, out of our trust in Him and our love for Him (in response to His love for us; 1 John 4:19), we obey Him (John 14:15; John 15:1-11). Our obedience leads us to a more vibrant experience of true life (John 10:10). Paul wrote in Romans 6:22, "But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life." As Christ-followers, we are free to live in obedience to God and be sanctified by Him. As part of that sanctification, we begin to experience eternal life even while on this earth (John 10:10; John 15:11). And, ultimately, we will spend eternity with God.