John L. Girardeau: Christ's righteousness, as our substitute, is perfectly spotless and provides infinite satisfaction before God for His elect

“The obedience which Christ, as the representative of his elect seed, rendered to the law is perfect; it is finished. The eye of justice, the scrutiny of Omniscience detect in it no blemish. It has been examined at the divine bar and judicially pronounced satisfactory. It cannot be invalidated; there is no contingency of failure in its results. But Christ’s seed representatively rendered that obedience in him. It therefore grounds, with absolute certainty, their everlasting holiness and happiness, their complete and indefectible life. The federal representative is in glory; the federal constituency must also be glorified. If not, the principle of representation is a figment, and the covenant of redemption breaks down amidst the jeers of hell.” (John L. Girardeau, "The Federal Theology: Its Import and Its Regulative Influence," with introduction by W. Duncan Rankin [Reformed Academic Press, 1994], pp. 45-46; quoted in a compilation by Lee Irons)