Beloved, do not believe every spirit, but test the spirits, whether they are of God; because many false prophets have gone out into the world. By this you know the Spirit of God: Every spirit that confesses that Jesus Christ has come in the flesh is of God, and every spirit that does not confess that Jesus Christ has come in the flesh is not of God. And this is the spirit of the Antichrist, which you have heard was coming, and is now already in the world. (1 John 4:1-3)
"Do not believe every spirit, but test the spirits" means that we shouldn't believe everything we hear just because someone says it is a message inspired by God. There are many ways to test teachers to see if their message is truly from the Lord. One is to check to see if their words match what God says in the Bible (1 John 2:22; 1 Cor. 12:3). Other tests include their commitment to the body of believers (1 John 2:19), their life-style (1 John 3:23, 24), and the fruit of their ministry (1 John 4:6). But the most important test of all, says John, is what they believe about Christ. Do they teach that Jesus is fully God and fully man? Our world is filled with voices claiming to speak for God. Give them these tests to see if they are indeed speaking God's truth.
John speaks of the spirits of teachers in a way similar to what Paul says about the spirits of the prophets in 1 Cor. 14:32. John is not referring here to demon possession, but to teachers who promote error. Believers have the Holy Spirit (1 John 3:24); but false prophets obey evil spirits. A true prophet is one who receives direct revelation from God. A false prophet claims to have received direct revelation from God but in fact promotes erroneous ideas.
When John states, “Jesus Christ has come in the flesh”, he seemed to be aiming this test at Docetists, which is a belief opposed as heresy in early Christianity that Christ only seemed to have a human body and to suffer and die on the cross. This test may also be aimed at the followers of Cerinthus who claimed that Jesus and “the Christ” were two separate beings, one physical and the other spiritual. In this letter, John is careful to use the name and title of Jesus Christ together to clearly express the complete union of the two titles in one person.
Cerinthus, a false teacher of John’s day, denied the Incarnation by teaching that the divine Christ descended on the human Jesus at His baptism and then departed before His crucifixion (1 John 2:22). John teaches that Jesus did not merely enter into an already existing human being, but He came as a human being. The Greek tense of the verb has come and the meaning of the noun flesh indicates that not only did Jesus come as a human being; He was still a human being even as John wrote. God the Son is forever fully God and fully man. He is immortal and has received a resurrected human body that does not age or die. A denial of Jesus’ full and true humanity proves that a teacher is not of God.
Some people believe everything they read or hear. Unfortunately, many ideas printed and taught are not true. Christians should have faith, but they should not be gullible. Verify every message you hear, even if the person who brings it says it's from God. If the message is truly from God, it will be consistent with Christ's teachings.
The antichrist will be a person who epitomizes all that is evil, and he will be readily received by an evil world. He is more fully described in 2 Thessalonians 2:3-12 and Revelation 13:1-18. The "spirit of the antichrist" is already here. Just before the world ends, one great antichrist will arise (Revelation 13:1-18; 19:20; 20:10). We do not need to fear these evil people, however. The Holy Spirit shows us their errors, so we will not be deceived. However, we must teach God's Word clearly and carefully to the peripheral, weak members among us so that they won't fall prey to these teachers who “come to you in sheep's clothing, but inwardly they are ravening wolves. “(Matthew 7:15).
Bob Deffinbaugh with Bible.org has a great commentary on Deuteronomy chapter 18 titled "False Prophets" at this link. One good quote from this link from Bob is - "False prophet’s play down the majesty and holiness of God. They try, as it were, to ‘bring God down’ to our level. They make us feel comfortable around “God” (or the “gods”), and they even seek to convince us that we can manipulate God to our advantage. The true prophets did just the opposite.'"
My question for you today is this: Do you think there are false prophets in our world today? Maybe you are attending a church that has a false prophet as a pastor or teacher! As Believers in our Lord Jesus Christ, we must always test the spirits of our church leaders and those who claim to be God’s messengers.
References: NKJV Holy Bible, Life Application Bible (NIV), the Nelson Study Bible.