Gal 3:17 And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect.Is this the covenant the has been replaced?
I believe so. Let's put that verse in context, and see if that is the one that has been replaced.
The first verse in the context (the previous verse) indicates that Christ inherited all the promises as the (only) chosen seed of Abraham:
"Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ." (Gal 3:16 KJV)
The next verse--the one you posted--states simply that THE LAW cannot disannul (or, cancel) the covenant that was promised to the chosen seed of Abraham, Jesus Christ:
"And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect." (Gal 3:17 KJV)
The next verse in the context expounds why THE LAW has no "authority" over the covenant:
"For if the inheritance be of the law, it is no more of promise: but God gave it to Abraham by promise." (Gal 3:18 KJV)
So, the inheritance is not by the Law, nor by race, nor by any other rule, but by promise. So, who are the inheritors of the promise? The children of God. And who are the children of God? That was revealed a few verses later:
"For ye are all the children of God by faith in Christ Jesus." (Gal 3:26 KJV)
So, if the promise is given strictly according to faith in Christ, then:
"There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise." (Gal 3:28-29 KJV)
So, to answer your question: yes, that was the old covenant that was replaced by the new. But it was not replaced by disannulment, but by fulfilment with the blood of Jesus Christ.
There is a very good explanation of the fulfillment by the blood of Christ in the book of the Hebrews, chapter 9. There is also this:
"For if that first covenant had been faultless, then should no place have been sought for the second. For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah: Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord. For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people: And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest. For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more. In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away." (Heb 8:7-13 KJV)
Note that the old covenant was ready to vanish away at the time the book of Hebrews was written. I suspect it had vanished completely by the time Jerusalem was completely destroyed during the days of vengeance around AD 70.
Philip