Cunningham:

There is no doubt that all the most eminent Calvinistic divines hold the infinite worth, or value of Christ’s atonement, its full sufficiency for expiating all the sins of all men.

A distinction was generally employed by the schoolmen, which has been often adverted to in this discussion, and which it may be proper to explain. They were accustomed to say, that Christ died sufficiently for all men, and efficaciously for the elect,–suffcienter pro omnibus, eficaciter pro electis. Some orthodox divines, who wrote before the extent of the atonement had been made the subject of full, formal, and elaborate discussion,–and Calvin himself among the rest,–admitted the truth of this scholastic position. But after controversy had thrown its full light upon the subject, orthodox divines generally refused to adopt this mode of stating the point, because it seemed to ascribe to Christ a purpose or intention of dying in the room of all, and of benefitting all by the proper effects of His death, as an atonement or propitiation; not that they doubted or denied the intrinsic sufficiency of His death for the redemption of all men, but because the statement whether originally so intended or not–was so expressed as to suggest the idea, that Christ, in dying, desired and intended that all men should partake in the proper and peculiar effects of the shedding of His blood. Calvinists do not object to say that the death of Christ–viewed objectively, apart from His purpose or design–was sufficient for all, and efficacious for the elect, because this statement in the first clause merely asserts its infinite intrinsic sufficiency, which they admit ; whereas the original scholastic form of the statement,–namely, that He died sufficiently for all,–seems to indicate that, when He died, He intended that all should derive some saving and permanent benefit from His death. The attempt made by some defenders of universal atonement to prove, that a denial of the universality of the atonement necessarily implies a denial of its universal intrinsic sufficiency, has nothing to do with the settlement of the state of the question, but only with the arguments by which the opposite side may be defended: and, therefore, I need not advert to it.

William Cunningham, Historical Theology, 2:331-332.