What does John 18:36 mean?

Critics of faith often claim that religion creates violence, war, and death. Historically, this is false: few wars in history were instigated by religious differences. With the notable exception of Islam, few religions have a history of engaging in active warfare. Further, Christ's reply to Pilate's investigation (John 18:33–35), given here, makes it clear that violence is not part of the Christ-follower's mandate for growing or defending faith. The goal of Jesus' ministry was not to establish a government, an empire, or a political group. His role as Messiah involves a spiritual kingdom, rooted in the hearts of those who believe (Hebrews 8:8–12), spread by example and evangelism (Matthew 5:13–16; 28:19).

At some point in history, however, Jesus will establish an earthly kingdom. It's noteworthy that when John—the same apostle who records this conversation with Pilate—describes Jesus' triumph at His second coming (Revelation 19:11–15). In that account, John speaks of the armies of heaven accompanying Jesus, but even then only describes Christ as "[striking] down the nations." At no point in the New Testament are Christians called on to take up arms as a means to establish an earthly kingdom in the name of Jesus.

Jesus' enemies have brought Him to the Roman governor, Pilate, with accusations of rebellion (Luke 23:2). Their claim is that Jesus seeks to rebel against Rome and establish His own state (John 19:12–15). That's a serious charge, and one Pilate needs to carefully consider (John 18:37), but it is crystal clear that Jesus is not seeking to overthrow the earthly rule of the Roman Empire (Matthew 27:18; Mark 15:10). It will be mob rule, and the threat of civil unrest (Matthew 27:24) which leads Pilate to hand over an innocent man for death (John 19:16).