For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Misinterpretation: I have heard several UPC preachers say that this Scripture does not say that people will be saved if they believe on Christ, it only says that they should be saved. Many of them then go on to say that a person who truly believes will be baptized in Jesus’ Name and speak in tongues, at which point they will actually be saved. I am ashamed to admit that I once taught this view.
Facts: The context of the Scripture makes it clear that Jesus is saying that those who believe on Him will be saved. To understand this point, let’s look at the verses immediately preceding John 3:16:
Joh 3:14-15 KJV
(14) And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up:
(15) That whosoever believeth in him should not perish, but have eternal life.
In this passage Jesus is explaining to Nicodemus how a man will be "born again." Nicodemus had asked Jesus, "How can these things be?" Jesus responds by comparing Himself with the bronze serpent that Moses created. The story of the bronze serpent is not very well known, so you may want to take a moment to read it. It is found in Numbers 21:1-9.
The summary of the story is that God sent fiery serpents into the camp of Israel, and many were bitten and were dying. God commands Moses to create a serpent and to lift it up on a pole. Moses does this by creating a serpent from bronze. When the serpent was lifted up, everyone who looked at the serpent was healed.
Returning to John, Jesus compares Himself to this serpent. He tells Nicodemus that He will be lifted up as well (referring to His death on the Cross) and that whoever believes on Him will have eternal life. So, once the Scripture is read in context, it becomes clear that Jesus is saying that those who believe on Him will be saved.
Interestingly enough, all of this is relating to being born again of the Spirit. The method that Jesus outlines is for a person to believe on Him. This is the antithesis of the UPC view that says a person must pray and pray and pray and humble themselves until they are "filled with the Holy Ghost" and speak in tongues.