Hebrews 10:1
1For the law, having a shadow of the good to come, not the very image of the things, can never with the same sacrifices year by year, which they offer continually, make perfect those who draw near.
The law holds only a shadow of the good to come, not the very image of the things; the same yearly sacrifices can never make perfect those who draw near. Wesley: the Mosaic dispensation is a bare, unsubstantial shadow of the gospel blessings, not the solid image of them, and cannot perfect the worshipers as to justification or sanctification.
Both camps say this together first: cultus fulfillment, not an atonement-extent fight. The shadow points forward; the true form is Christ. Arminians hear that the yearly cycle never completed what it pictured; the good things are sincerely given in the gospel, and perfection is found only in the once-for-all offering that follows.
Calvin: under the Law was shadowed forth only in rude and imperfect lines what is under the Gospel set forth in living colors. The Law was not useless; the fathers were helped by the representation; yet our condition is much more favorable. The same Christ, the same righteousness, sanctification, and salvation are exhibited to both; the difference is in the manner of setting them forth.
The annual sacrifices prove their own inability. Perfection is not delayed for lack of sincerity in the worshiper; it is delayed because the shadow cannot do what only the substance can. The cultus argument is about once-for-all fulfillment in Christ, not about inventing a limited-versus-general quarrel here.