Paul writes to the Ephesian Christians that the covenants of promise are now for them as much as for the Jewish people.
What covenant of promise is Paul writing about? The Covenant of grace which God made with Abraham:
"And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed." (Genesis 12: 3)
"And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed." (Galatians 3: 8)
How do these blessings pass onto us? Through Jesus:
"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." (Galatians 3: 16)
"26For ye are all the children of God by faith in Christ Jesus. 27For as many of you as have been baptized into Christ have put on Christ. " (Galatians 3: 26-27)
So, even though you and I may not be Jews by birth, we have received the spirit of adoption, making us sons and daughters of God the Father through Jesus (Romans 8: 15-17).
This revelation means that the New Covenant promised in the Old Testament is for us today:
10For 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:
11And 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.
12For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more." (Hebrews 8: 10-12)