Sure, there was. The overarching one covenant of grace, which connects all believers, New and Old, proves that the church existed from Adam. It's sad you do not see that.
Could you give a Bible verse anywhere that speaks of some overarching covenant of grace? The church did not exist from Adam. Paul said the church was a mystery. Why was the church a mystery? There is nothing in the Old Testament that says the Gentiles will be included.
Ephesians 3
"
For this reason I, Paul, the prisoner of Christ Jesus for the sake of you Gentiles— 2 if indeed you have heard of the stewardship of God’s grace which was given to me for you; 3 that by revelation there was made known to me the mystery, as I wrote before in brief. 4 [a]By referring to this,
when you read you can understand my insight into the mystery of Christ, 5 which in other generations was not made known to the sons of men, as it has now been revealed to His holy apostles and prophets [c]in the Spirit; 6 to be specific, that the Gentiles are fellow heirs and fellow members of the body, and fellow partakers of the promise in Christ Jesus through the gospel, 7 of which I was made a minister, according to the gift of God’s grace which was given to me according to the working of His power. "
There was no church in the Old Testament. There was the nation of Israel under the Mosaic Covenant, which they violated. The word in Greek used to speak of Israel is translated as assembly/gathering/congregation. Church is not the prominent definition, though it is one of the words it can be translated to. In Hebrew, there is, unlike Greek, a separate word used for church. Greek does not have a separate word.
Well, I think you should re-read the Abrahamic covenant, I believe you're missing out on a lot, or you're just denying it.
Genesis 15
"17 It came about when the sun had set, that it was very dark, and behold, there appeared a smoking oven and a flaming torch which passed between these pieces. 18 On that day the Lord made
a covenant with Abram, saying,
“To your [t]descendants I have given this land,
From the river of Egypt as far as the great river, the river Euphrates:
19 the Kenite and the Kenizzite and the Kadmonite 20 and the Hittite and the Perizzite and the Rephaim 21 and the Amorite and the Canaanite and the Girgashite and the Jebusite.”"
Genesis 17
"6 I will make you exceedingly fruitful, and I will make nations of you, and kings will come forth from you. 7 I will establish My covenant between Me and you and your [f]descendants after you throughout their generations for an everlasting covenant, to be God to you and to your [g]descendants after you. 8 I will give to you and to your [h]descendants after you, the land of your sojournings, all the land of Canaan, for an everlasting possession; and I will be their God.”
[This is an ethnic covenant. There is no salvation here. The actual covenant is next here]
9 God said further to Abraham, “Now as for you, you shall keep My covenant, you and your
descendants after you throughout their generations. 10 This is My covenant, which you shall keep, between Me and you and your [j]descendants after you: every male among you shall be circumcised. 11 And you shall be circumcised in the flesh of your foreskin, and it shall be the sign of the covenant between Me and you. 12 And every male among you who is eight days old shall be circumcised throughout your generations, a servant who is born in the house or who is bought with money from any foreigner, who is not of your [k]descendants. 13 A servant who is born in your house or who is bought with your money shall surely be circumcised; thus shall My covenant be in your flesh for an everlasting covenant.
14 But an uncircumcised male who is not circumcised in the flesh of his foreskin, that person shall be cut off from his people; he has broken My covenant.”
[Again, this covenant is ethnic. It is NOT salvific.]
15 Then God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but [l]Sarah shall be her name. 16 I will bless her, and indeed I will give you a son by her. Then I will bless her, and she shall be a mother of nations; kings of peoples will [m]come from her.” 17 Then Abraham fell on his face and laughed, and said in his heart, “Will a child be born to a man one hundred years old? And will Sarah, who is ninety years old, bear a child?” 18 And Abraham said to God, “Oh that Ishmael might live before You!” 19 But God said, “No, but Sarah your wife will bear you a son, and you shall call his name [n]Isaac; and I will establish My covenant with him for an everlasting covenant for his [o]descendants after him. 20 As for Ishmael, I have heard you; behold, I will bless him, and will make him fruitful and will multiply him exceedingly. He shall [p]become the father of twelve princes, and I will make him a great nation. 21 But My covenant I will establish with Isaac, whom Sarah will bear to you at this season next year.” 22 When He finished talking with him, God went up from Abraham."
Now, there are promises God made outside of the covenants. The one Gentiles care about is the one that says that in Abraham's seed [singular], all the nations of the world will be blessed. The one Paul said is the gospel given to Abraham. Abraham probably did not understand it, since in Ephesians Paul said that the inclusion of Gentiles had not been made known to any man until Paul's time.
You should see, the Abrahamic covenant extends to all believers, not just ethnic Jews. And this is through faith in Christ, who is the promised "seed" that brings blessing to all nations. If you would rather not do the work yourself, I can and will point out the scriptures that teach Gentiles are grafted into this covenant through faith. Thereby, inheriting promises as Abraham's spiritual descendants rather than through physical lineage.
This is a problem of eisegesis vs. exigesis. God made a promise with Abraham (not a covenant), after Abraham was to sacrifice Isaac. It is that promise that Paul speaks of in relation to the uncircumcised being able to be saved by faith.
"15 Then the angel of the Lord called to Abraham a second time from heaven, 16 and said, “By Myself
I have sworn, declares the Lord
, because you have done this thing and have not withheld your son, your only son, 17 indeed I will greatly bless you, and I will greatly multiply your [e]seed as the stars of the heavens and as the sand which is on the seashore; and your [f]seed shall possess the gate of [g]their enemies. 18
In your [h]seed all the nations of the earth shall be blessed, because you have obeyed My voice.” 19 So Abraham returned to his young men, and they arose and went together to Beersheba; and Abraham lived at Beersheba."
This is the promise. It is not the Abrahamic covenant. This is what Paul uses in Romans 4 in speaking of justification by faith for the circumcised and the uncircumcised.
As for Romans 11 with the tree that Gentiles are grafted into... that is NOT the Abrahamic covenant. It is the NEW covenant in Jesus blood that is a replacement for the flawed Mosaic covenant. The Jews who are in it are the disciples, and those Jews who believed in Christ from the beginning. The Gentiles are foreign branches who are grafted in. (God made the new covenant with the Jews only, but by His kindness and mercy, extended it to the Gentiles after the Jews rejected the Messiah.) Those Gentiles can be cut off if they do not continue in the kindness of God. The Jews were removed by God's severity. Why severity? They are His chosen people, living on His kindness, and they rejected His Messiah. So they are cut off. However, if they return in belief, God will reattach them. No such contingency is mentioned for Gentiles.
This is the important passage at the end;
"30 For just as you once were disobedient to God, but now have been shown mercy because of their disobedience, 31 so these also now have been disobedient, that because of the mercy shown to you they also may now be shown mercy. 32 For God has shut up all in disobedience so that He may show mercy to all."
For just as you [Gentiles] were disobedient to God, but now have been shown mercy because of their [Israel/Jews] disobedience, so these [Israel/Jews] also now have been disobedient, that because of the mercy shown to you [Gentiles] they [Israel/Jews] also may be shown mercy.
This is how God has chosen to save His elect people of the Jews and the Gentiles. This is the circle. Gentiles disobedient, Jews rejected the Messiah [their disobedience], God shows mercy and Gentiles can be/are saved, Jews are still disobedient that God may show His wayward people the same mercy He showed to the Gentiles, and they will be saved.
I do suggest, though, you do the work and see for yourself.
I have done work. It will never be completed, as there is a lot to it.