Matthew 23:15
"Woe unto you, scribes and Pharisees, hypocrites! For ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell than yourselves."
In Christ’s day, it was customary for the religious leaders to propagate their self-righteous religious doctrines, much like ‘missionary societies’ today, and yet, once they became proselytes or religious converts, Christ pronounced on them this condemnation:“Ye make him twofold more the child of hell than yourselves.” All their zeal did not make them any more fit for heaven than those they proselytized, "Brethren, my heart's desire and prayer to God for Israel is, that they might be saved. For I bear them record that they have a zeal of God, but not according to knowledge. For they being ignorant of God's righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God" (Romans 10:1-3).
Their followers become twofold more the children of hell than them in that, not only have they never been made to see their condemned state as unconverted sinners, but by profession, think themselves righteous, by their acts of penance, their supposed free-will decision, or dedication to the god in whom they trust, Yet, it is false righteousness that is nothing but filthy rags before a holy God, "But we are all as an unclean thing, and all our righteousnesses are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away" (Isaiah 64:6).
We are not to believe every spirit. Many false prophets have gone out into the world, "Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world. Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: and every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and that is the spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world. Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world. They are of the world: therefore speak they of the world, and the world heareth them" (1 John 4:1-5).
All who are the LORD’s by electing grace, Christ has redeemed, and in time will call to Himself by His Spirit. All that He calls in His effectual Grace in Christ, He does cause to confess their lost estate and to see that it is for them that the LORD Jesus came into the world, “to seek and to save that which is lost” (Luke 19:10). The whole of salvation is in Him. Upon the completion of His death at the cross, God the Father once and forever imputed Righteousness to the spiritual account of every one of those for whom Christ paid the debt. He earned and established that Righteousness that was equal to God's Law and Justice in His Holy Life, and then finished the work in His death on the cross. "Much more then, being now justified by His blood, we shall be saved from wrath through Him. For if, when we were enemies, we were reconciled to God by the death of His Son, much more, being reconciled, we shall be saved by His life. And not only so, but we also joy in God through our LORD Jesus Christ, by whom we have now received the reconciliation " (Romans 5:9-11). This is the one, unique, Good Hope that all the LORD’S children possess and that the LORD reveals in them. Any other hope is a false and condemning hope.
It's impossible in this life for a human being to realize just how much of a sinner they are. But once you get a glimpse of what sin is and a little bit of a glimpse of how much of a sinner you really are, then you begin to realize how much of a Savior you really need. And then when by the grace of God you realize just exactly how much of a Savior Jesus really is, that's when you realize that any and other hope you had in any one or anything else is nothing but a sin in the eyes of God.