Hebrews 7:15-19 (ESV)
This becomes even more evident when another priest arises in the likeness of Melchizedek,  who has become a priest, not on the basis of a legal requirement concerning bodily descent, but by the power of an indestructible life.  For it is witnessed of him,
"You are a priest forever,
after the order of Melchizedek."
 On the one hand, a former commandment is set aside because of its weakness and uselessness  (for the law made nothing perfect); but on the other hand, a better hope is introduced, through which we draw near to God.
For the law made nothing perfect. Did you get that? The law made nothing perfect. Neither does it make anything perfect. It didn’t then, it doesn’t now. Perhaps you read that this is talking only of the levitical ceremonial laws concerning food, worship and so on. But I don’t read it that way. Today people wittingly and unwittingly make all sorts of new laws, for themselves and others. They throw these laws up into the arena of “sanctification”. Some sort of step ladder or something that you climb, slowly getting better at following the law. Actually, they just replace God’s law, for laws of their own they find easier to follow. The law makes nothing perfect. It condemns. I try, TRY, to live by the ten commandments. They hardly make me perfect. Perhaps if I could master those I would have time for new laws, but I have a hard enough time with those ten. The law makes nothing perfect. But on the other hand….
A better hope has been introduced, Jesus Christ, is our hope. He does make us perfect. The law can’t do it, but the blood of Christ can, and through him, and the forgiveness of sins, we draw near to God.