“The gospel method of sanctification, as well as of justification, lies so far out of the ken (i.e., understanding/perception-J.F.) of natural reason, that if all the rationalists in the world, philosophers and divines, had consulted together to lay down a plan for repairing the lost image of God in man, they had never hit upon that which the divine wisdom has pitched upon, viz, that sinners should be sanctified in Christ Jesus, 1 Cor i. 2, by faith in him, Acts xxvi. 18. Nay, being laid before them, they would have rejected it with disdain, as foolishness, 1 Cor i. 23.
In all views which fallen man has, towards the means of his own recovery, the natural bent is to the way of the covenant of works (legalism; “do to live”-J.F.). This is evident in the case of the vast multitudes throughout the world, embracing Judaism, Paganism, Mahometanism (Islam-J.F.), and Popery (Roman Catholicism-J.F.). All these agree in this one principle, “That it is by doing men must live,” though they hugely differ as to the things to be done for life.”
(Works of Thomas Boston, vol. 7, “The Marrow of Modern Divinity,” p. 146; emphasis mine).