Believers should witness for the Savior every opportunity they have. Even still, though, nowhere in Scripture does it teach that a Christian is responsible for an unbeliever going to hell because he missed an opportunity to share the gospel.
Commonly misquoted, Ezekiel 3:18–19 reads, “When I say to the wicked, ‘you shall surely die,’ and you give him no warning, nor speak to warn the wicked from his wicked way, to save his life, that same wicked man shall die in his iniquity; but his blood I will require at your hand. Yet, if you warn the wicked, and he does not turn from his wickedness, nor from his wicked way, he shall die in his iniquity; but you have delivered your soul.” In context, God is speaking to Ezekiel, a person appointed as a watchman over Israel. A watchman was one who stood on the city wall, hilltop, or watchtower to alert the city of impending danger. Ezekiel fulfilled his responsibility and gave the people time to secure the gates and prepare their defense.
With that context understood, let’s note a few points. First, Ezekiel 3:18–19 references the physical, not the spiritual. The scene is the Babylonian destruction of Jerusalem. If the wicked did not heed God’s warning through Ezekiel, they could expect physical death. By giving this warning, Ezekiel delivered himself from the responsibility of the coming judgment. Anyone who ignored his warning could only blame himself. In no way is this talking about believers’ responsibility to witness and warn non-Christians of eternal separation from God.
Secondly, a believer is not a “watchman” over the world in the way that Ezekiel was a watchman over Israel. Today’s watchmen over the world are the Holy Spirit and the Scriptures. John 16:7–11 tells us, “Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you. And when He has come, He will convict the world of sin, and of righteousness, and of judgment: of sin, because they do not believe in me; of righteousness, because I go to My Father and you see Me no more; of judgment, because the ruler of this world is judged.” As the Holy Spirit works, God uses Scripture to bring people to Christ: “So then faith comes by hearing, and hearing by the word of God” (Romans 10:17).
Ezekiel 3:18–19 simply should not be used in evangelism. God was speaking to Ezekiel about his responsibility as a watchman to the nation of Israel. God was not speaking to us about our responsibility to witness.
We should use every opportunity to bring Christ to people, always recognizing only God can bring people to Christ. John 6:44 reminds us, “No one can come to Me unless the Father who sent Me draws him; and I will raise him up at the last day.” Scripture never leaves the eternal destiny of an unbeliever in our hands.