New Defender's Study Bible Notes
1:8 not that Light. What a testimony to John the Baptist! He was so Christlike in his life and teachings that people kept mistaking him for the promised Messiah, requiring John in his gospel (inspired by the Holy Spirit) to assure people that, despite all appearances, John the Baptist was not Christ.
1:9 lighteth every man. Even though some people live and die without ever hearing of Jesus, the witness imprinted by Him on His creation is such conclusive evidence that there is a Creator who is omnipotent, omniscient, holy and loving, that those who reject or ignore it are “without excuse.” See notes on Romans 1:20; Psalm 19:1-6; etc. He has also placed the light of conscience in each person (Romans 2:14-15), but that too is rejected in most instances.