How is justification an act of God's free grace?
Although Christ, by his obedience and death, did make a proper, real, and full satisfaction to God’s justice in the behalf of them that are justified;[1] yet inasmuch as God accepteth the satisfaction from a surety, which he might have demanded of them, and did provide this surety, his own only Son,[2] imputing his righteousness to them,[3] and requiring nothing of them for their justification but faith,[4] which also is his gift,[5] their justification is to them of free grace.[6]