“How shall we distinguish Christ’s active obedience from His passive obedience? Shall we say that He accomplished His active obedience by His life and accomplished His passive obedience by His death? No, that will not do at all. During every moment of His life upon earth Christ was engaged in His passive obedience. It was all for Him humiliation, was it not? It was all suffering. It was all part of His payment of the penalty of sin. On the other hand, we cannot say that His death was passive obedience and not active obedience. On the contrary, His death was the crown of His active obedience. It was the crown of that obedience to the law of God by which He merited eternal life for those whom He came to save.
Do you not see, then, what the true state of the case is? Christ’s active obedience and His passive obedience are not two divisions of His work, some of the events of His earthly life being His active obedience and other events of His life being His passive obedience; but every event of His life was both active obedience and passive obedience. Every event of His life was a part of His payment of the penalty of sin, and every event of His life was a part of that glorious keeping of the law of God by which He earned for His people the reward of eternal life. The two aspects of His work, in other words, are inextricably intertwined. Neither was performed apart from the other. Together they constitute the wonderful, full salvation which was wrought for us by Christ our Redeemer.”
J. Gresham Machen in the book God Transcendent (190-191)