What does John 12:49 mean?

Pharisees who challenged Jesus claimed that He did not have the evidence or authority to support His own claims (John 8:13). Contrary to this, Jesus had been pointing to various proofs (John 5:30–40). In doing so, Jesus also noted that His words were those of God the Father Himself (John 8:19). What Christ says here is not a rejection of His own divinity—He is not saying, "I am not God, but I speak for God." Rather, He is pointing out that the words He says don't merely come from some physical human form. They are part of God's will and God's plan for the One He has sent (John 8:28; 12:27–36).

This ties into Jesus' earlier statements indicating that to reject Him is to reject God (John 12:44–48). There is only one way for mankind to be saved, and that is through belief in God the Son (John 3:16–18, 36). Jesus is not merely "like" God, He is the exact image—precisely the same thing—as God the Father (Hebrews 1:3; Colossians 1:15). Anyone who denies that Jesus is who He claimed to be will find themselves separated from God for all of eternity (Revelation 20:11–15).