Thomas Aquinas

“ Further, given a sufficient cause, nothing more seems to be required for the effect. But Christ's Passion is the sufficient cause of our salvation; for the Apostle says (Rom. 5:10) : "If, when we were enemies, we were reconciled to God by the death of His Son: much more, being reconciled, shall we be saved by His life." Therefore sacraments are not necessary for man's salvation.
On the contrary, Augustine says (Contra Faust. xix) : "It is impossible to keep men together in one religious denomination, whether true or false, except they be united by means of visible signs or sacraments." ”

“ For as time went on sin gained a greater hold on man, so much so that it clouded man's reason, the consequence being that the precepts of the natural law were insufficient to make man live aright, and it became necessary to have a written code of fixed laws, and together with these certain sacraments of faith. ”

“ The sacrament of Melchisedech which preceded the Law is more like the Sacrament of the New Law in its matter: in so far as "he offered bread and wine" (Gn. 14:18) , just as bread and wine are offered in the sacrifice of the New Testament. ”