Heb 8:6 6 But now hath he [Christ] obtained a more excellent ministry, by how much also he[Christ] is the mediator of a better covenant, which was established upon better promises. The Lord Jesus Christ, in His Death, Established and enacted a Better Covenant for God's Elect, the People of God, God's Covenant People, known under the OC as Israel ! Under the OC God's People had duties they were required to perform, such duties that would establish them as God's Covenant People. Now those duties under that Covenant, that God did enjoin for them to perform, now under the NC or the Better Covenant, inaugurated by Jesus Christ and which He mediates. The word better is the greek word kreittōn and means: more useful, more serviceable, more advantageous 2) more excellent Now the word is a derivative of kratos which means: force, strength 2) power, might: mighty with great power a) a mighty deed, a work of power 3) dominion By this Better Covenant, more Excellent, God now puts forth strength in them to will and to do of His good pleasure. He causes them to do His Will by His Power put forth in them ! Case in point, God did command His Covenant People Israel here Deut 10:16 16 Circumcise therefore the foreskin of your heart, and be no more stiffnecked. Now under the New Covenant or better Covenant God makes a promise Deut 30:6 6 And the Lord thy God will circumcise thine heart, and the heart of thy seed, to love the Lord thy God with all thine heart, and with all thy soul, that thou mayest live. Thats a Better Promise from a Better Covenant, that is Mediated through Jesus Christ. This Promise is confirmed to the seed through Christ Rom 4:16, His Death and Blood of the New Covenant Matt 26:28 But this is only for God's Elect, the Seed, God's Covenant People not only in Israel, but throughout the World !