In Rev.19:10, we read: And I fell at his feet to worship him. And he said to me, 'Do not do that; I am a fellow servant of yours and your brethren who hold the testimony of Jesus; worship God. For the testimony of Jesus is the spirit of prophecy'.
John was so excited that he fell down to worship the one who showed him all these things. In the immediate reply of that angel to John, we see the attitude of true servants of God: "Don't worship me. Don't get attached to me". A true servant of God will always connect you to Christ the Head, and never allow you to be attached to himself. To attract people to ourselves is to get them to worship us. Anyone who does that is not a servant of God, but a counterfeit. He has the spirit of the Antichrist who draws people to himself.
In Christendom today, unfortunately we have many such counterfeits through whom many believers are deceived. Many believers almost worship some preachers. They live by every word that proceeds out of the mouths of those preachers - instead of living by the words that proceed from God's mouth. They seek to know God's will through a man, instead of going directly to God - and these preachers encourage them!! This is idolatry!! There is a lot of so-called "prophecy" in some Christian circles today that makes believers dependent on the "prophet". All such prophets are false prophets.
But here we see the angel saying, "I am just a servant of the Lord, as you are. Worship God alone".
To hold to "the testimony of Jesus" means that we hold forth today the same torch that Jesus held forth in his earthly life. As He did, we too proclaim, "Blessed are the pure in heart for they shall see God".
Here we have a clear definition of true prophecy: "THE TESTIMONY OF JESUS". That means two things basically:
First of all, true prophecy always draws attention to Christ, and exalts Him. When Jesus is lifted up, He draws all men to Himself. The Holy Spirit Who gives the gift of true prophecy always glorifies Christ (Jn.16:14). Any prophecy that draws attention to yourself or to another man or that exalts you or any other man can be written off as a false prophecy.
Secondly, true prophecy proclaims all that Jesus proclaimed in His preaching. There is no compromise in true prophecy. It will be full of grace and truth, but it will speak ALL of the truth - in love.
So to test prophecy, we must first of all know what Jesus emphasised in His teaching. If we read the gospels and see what Jesus emphasised, we will have a touchstone by which to test all that we hear as "prophecies" today. If however, we haven't studied the gospels carefully, the chances are that we will be deceived. Because 99% of what goes under the guise of "Christian prophecy" today is not proclaiming what Jesus proclaimed.
You just have to read through the sermon on the mount (Matt.5 to 7) and compare it with what you hear in most churches today to realise that.