From Ursinus' commentary on the Heidelberg Catechism, specifically Q: 37...
"Obj. 4 If Christ made satisfaction for all, then all ought to be saved. But all are not saved. Therefore, he did not make a perfect satisfaction.
"Ans. Christ satisfied for all, as it respects the sufficiency of the satisfaction which he made, but not as it respects the application thereof; for he fulfilled the law in a two-fold respect. First, by his own righteousness; and secondly, by making satisfaction for our sins, each of which is most perfect. But the satisfaction is made ours by an application, which is also twofold; the former of which is made by God, when he justifies us on account of the merit of his Son, and brings it to pass that we cease from sin; the latter is accomplished by us through faith. For we apply unto ourselves, the merit of Christ, when by a true faith, we are fully persuaded that God for the sake of the satisfaction of his Son, remits unto us our sins. Without this application, the satisfaction of Christ is of no benefit to us."
(Zacharias Ursinus translated by Rev. G. W. Williard, The Commentary of Dr. Zacharias Ursinus on the Heidelberg Catechism, 3rd American edition, Cincinnati, OH: Elm Street Printing Company, 1851, p. 215)