The covenant of grace that God has made with spiritual Israel has no conditions in it for them to meet. From beginning to end it contains a declaration of what God will do for them. This includes, (1) the putting of His laws into their minds and writing them in their hearts, (2) His being to them a God, and their being to Him a people, (3) their all being brought to the knowledge of Him, from the least to the greatest, (4) His being merciful to their unrighteousness, (5) His forgiving their iniquity, and (6) His remembrance of their sins no more. All these things are secured in and by the new covenant and God's people have nothing whatsoever to do with their coming to pass.
    The old covenant that God made with the natural Israelites was a conditional covenant, and in one way or another they all broke it. But the new covenant is not according to that former covenant, in which they did not continue, even though God was a husband unto them (Jer. 31:32). If it was conditional on their part then it would be according to the old, and spiritual Israel would brake it just like national Israel broke the first. But this covenant will not be broken, for it was made between God the Father, God the Son, and God the Holy Spirit. They all have their office works to perform, and all those works will be carried out to perfection, the end result being that all spiritual Israelites "shall be saved in the Lord with an everlasting salvation" (Isa. 45:17). He will be to them a God, and they shall be to Him a people---no uncertainty about it.
    There is much for God's people (spiritual Israel) to be doing, for they are under law to Christ, and righteous living should characterize their everyday conduct and deportment. But in that eternal covenant that secures their final destiny, they have nothing to perform, for in order for the stipulations of that covenant to be perfectly met, God alone must carry them out and complete them, otherwise not one living soul would ever see heaven.