As usual, Augustus Toplady describes God’s free grace very well. Note that when we (in Reformed theology) talk about salvation or justification by grace alone we mean “apart from all works and every work of ours before, along with, or after regeneration.”
We never know so much of heaven in our own souls, nor stand so high upon the mount of communion with God, as when his Spirit, breathing on our hearts, makes us lie low at the footstool of sovereign grace, and inspires us with this cry, O God, be mine the comfort of salvation, but thine be the entire praise of it.
Let us briefly apply the rule and compass of God’s word, to the several parts, of which salvation is composed; and we shall soon perceive that the whole building is made up of grace, and of grace alone. Do you ask, in what sense I here take the word grace? I mean, by that important term, the voluntary, sovereign, and gratuitous bounty of God; quite unconditionated by, and quite irrespective of, all and every shadow of human worthiness, whether antecedent, concomitant [accompanying], or subsequent, This is, precisely, the scriptural idea of grace: to wit, that it [i. e. salvation in all its branches] is not of him that willeth, nor of him that runneth; but of God, who showeth mercy. And thus it is, that grace reigneth, unto the eternal life of sinners, through the righteousness of Jesus Christ our Lord.