Ralph Erskine on the covenant of works and Christ the Surety

[Reformed Covenanter]

... There behoved indeed to be a secret reserve in the covenant of works, whereby the perfect obedience of another was not excluded: For, if the covenant of works had absolutely excluded a surety in our room, then the covenant of grace had been excluded, and our salvation had been impossible after our fall; but though’ the covenant of works did not exclude a surety, yet that covenant did neither provide nor reveal a surety: This is done in the covenant of grace, which is Christ as surety fulfilling for us the covenant of works, in all the articles of it. Now, is truth and faithfulness at any loss here?

No, the truth of the promise & threatening both of the law of works, is fulfilled. On the one hand, the promise of eternal life made to perfect obedience; which, though’ we forfeited in our own person, yet we recover in the person of Christ; the promise of life upon the ground and condition of perfect obedience being fulfilled to us in him, who hath yielded that perfect obedience in our room: On the other hand, divine truth and faithfulness, in the threatening of the law, which was death, is glorified, in that it is fulfilled upon the surety; while we, who came under the sentence of death in the first Adam, undergo that death in the second. ...

For more, see Ralph Erskine on the covenant of works and Christ the Surety.