By speaking of a 'new' Covenant, God at once renders the former Covenant obsolete; and whatever becomes obsolete and loses its force is virtually annulled.
Love never fails. But, whether it be the gift of preaching, it will be done with; whether it be the gift of 'tongues,' it will cease; whether it be knowledge, it, too, will be done with.
Our fitness comes from God, who himself made us fit to be ministers of a New Covenant, of which the substance is, not a written Law, but a Spirit. For the written Law means Death, but the Spirit gives Life.
But Jesus, as we see, has obtained a ministry as far excelling theirs, as the Covenant of which he is the intermediary, based, as it is, on better promises, excels the former Covenant.
But, finding fault with the people, God says-- '"Behold, a time is coming," says the Lord, "when I will ratify a new Covenant with the People of Israel and with the People of Judah--
And that is why he is the intermediary of a new Covenant; in order that, as a death has taken place to effect a deliverance from the offenses committed under the first Covenant, those who have received the Call may obtain the eternal inheritance promised to them.