Sir, I do not dismiss Hebrews or any other book of God's Word, but you must weigh what you read in one part of Scripture to the whole of Scripture.
If you know anything about Calvinism, then you know that we are against teaching that simple recitation of a prayer will save you.
If you ever took a history class, then you know that Calvinists over the centuries have been ridiculed for their strict moral codes. We believe we can contribute nothing to our salvation. It is only by the mere pleasure of God and by His Grace. Yet we teach that the true Christian will stirve to please God because a true Christian is a new creature. Not saying that we are made perfect. Far from it, but we teach that the true Christian will strive for perfection out of a love for God.
John 10
25 Jesus answered them, I told you, and ye believed not: the works that I do in my Father's name, they bear witness of me.
26 But ye believe not, because ye are not of my sheep, as I said unto you.
27 My sheep hear my voice, and I know them, and they follow me:
28 And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand.
29 My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father's hand.
30 I and my Father are one.
We are in the Father's hands. Who can remove us? It is the Father who grants faith. Does He take it from us?
True, many have made a false confession and are not truly saved. While they may show zeal for a while, they will fall away. Some shall perform even great works, but they are not saved. They may even have false assurance because God has blinded their eyes from the truth, but they shall meet the destruction which we all deserve.
Thanks be to God that salvation rests not in our hands but in His hand. For if it were left up to us, we should surely all fall into hell.