1Beloved, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world.
2By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God;
3and every spirit that does not confess Jesus is not from God; this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world.
4You are from God, little children, and have overcome them; because greater is He who is in you than he who is in the world.
5They are from the world; therefore they speak as from the world, and the world listens to them.
6We are from God; he who knows God listens to us; he who is not from God does not listen to us By this we know the spirit of truth and the spirit of error.
Continuing with the message of the Holy Spirit, John warns us against false teachings and explains how to discern between the Gospel and false teachings. many think, through sparse readings of the scriptures, that the coming of the antichrist is but a one time event to set forth the end of times. John uses the principle of the antichrist here to tell us that he is already here. Satan is the king of this world, Christ is the King of Kings of the Kingdom.
I take comfort in this, for those of us that are saved are not of this world. this is where we draw our power over the fear of death, for it simply releases us from this world to where we belong.
If you go to a church and they do not preach from the basis of Christ and Him crucified, then it is not a church of God, period. If what someone is teaching is linked to the Gospel and backed by the Bible, then it is of God. Being of God yourself is another good indicator. Years ago I was invited to church by someone. The Spirit churned inside me just by entering the building. I was not at home. This is what John was talking about previously about the Spirit convicting you. You will KNOW if it is where God wants you to be or not. We might not understand why.
God gave us His Word not just to learn and communicate with Him, but also to protect us. By comparing all we see and hear to the Bible, we can discern if it is Godly or not. Nowadays we have websites that can reference things topically through the bible. Next time you are questioning something spiritually, reference The Word. Therein lies the answer.