"William Ames (1576-1633). Anglican, then Presbyterian. Ministered in England as Cambridge Calvinist and in Holland as pastor and professor and advisor at the Synod of Dort. Closest disciple of William Perkins. Greatly influenced American Puritans. Wrote The Marrow of Theolgy , the standard Puritan systematic theology; and Cases of Conscience, important work on Biblical ethics; many others."
Here is Puritan heretic William Ames revealing why Romans 11:6 is such an important passage in discerning salvation conditioned on the sinner's efforts versus salvation conditioned on the work of Jesus Christ alone -- His atoning blood and imputed righteousness:
"The new covenant differs from the old in many ways....the old required perfect obedience of works to be performed by man of his own strength prior to the carrying out of the promise, which would then be in the form of a reward. But the present covenant requires no properly called or prior condition, but only a following or intermediate condition (and that to be given by grace as a means to grace), which is the proper nature of faith" (William Ames, The Marrow of Theology, pp. 150-151).
If "grace" enables a person to fulfill "a following, or intermediate condition" (i.e., a work) "as a means to grace," then "grace is no more grace" (Romans 11:6). If ANY AMOUNT of works, conditions, prerequisites, running, or willing (cf. Romans 9:16) are prefaced with the word "grace" then the concept of works salvation completely vanishes since all of this "non-meritorious, instrumental-condition-meeting" would be "according to grace" or "all of grace."
"Now [to one] working, the reward is not counted according to grace, but according to debt" (Romans 4:4).
If consistent, Ames must say that "to him that worketh is the reward NOT reckoned of debt, but of grace" since this working was "given by grace as a means to grace" (blatantly contradicting Romans 4:4).
