There are church members who reveal themselves to be members only in name. When Christ returns it will become plain that they are not and never were members of His church. In the New Testament days many of those were called Pharisees. There were also those who knew their sins and hated them, and were called publicans.
To show the faith that some of these publicans had, Jesus said in Matthew 9:12, 13 , "They that be whole need not a physician, but they that are sick. But go ye and learn what that meaneth, I will have mercy, and not sacrifice: for I am not come to call the righteous, but sinners to repentance."
Take hold of that truth. If you think that you have no sin, take hold of the fact that Jesus says that then you do not need Him. In the measure that we think we are not guilty before God, we have no need for Christ and His cross. In the measure that we know how sinful we are, we see how much we need Christ, and how much we owe God thanks and praise for sending His own Son into our flesh to save us. In that measure we will appreciate His love and grace that sent His Son.
Christ has mercy on those sinners who do not think that by their own works, such as bringing sacrifices, giving God something, they earn salvation. The Pharisees were that kind of people; but for them there was and is not salvation.
Examine your life carefully. Learn more and more how guilty you are in yourself. Be thankful, and grow in thanksgiving for what God has done for you, not for what you think you did for Him.
Read God's law carefully. Stand very often before the mirror of God's law to see yourself as He sees you. Then, as that publican, you will, by God's grace, cry out for mercy, and not boast of what you did, as that Pharisee so wickedly did. Seek salvation in Christ, not in any of your own works, or even in your desire for salvation.
Read: Matthew 9:9-13 .
John Calvin on Hebrews 7:3: "... Melchisedec is not to be considered here, as they say, in his private capacity, but as a sacred type of Christ; nor ought we to think that it was accidentally or inadvertently omitted that no kindred is ascribed to him, and that nothing is said of his death; but on the contrary, that this was done designedly by the Spirit, in order to give us an idea of one above the common order of men. There seems therefore to be no probability in the conjecture of those who say that Melchisedec was Shem the son of Noah; for if we make him to be some known individual, we destroy this third likeness between Melchisedec and Christ ... It seems not to be worth one’s while to refute the delirious notions of those who dream that Christ himself, or the Holy Spirit, or an angel, appeared at that time ..."