What then do you make of Col. 1:24? Certainly Our Lord merited infinite grace through His passion, death, and resurrection. The cross, the shedding of Our Lord’s most Precious Blood, is all-sufficient for our salvation. Yet the gift of salvation Our Lord won for us must be mediating to each of us in time and space. Christ could have simply declared all men everywhere and always saved…but neither of us believes that to be the case. We both believe that we must cooperate with Christ’s grace by choosing to receive His gift. An act of the will is required on our part. Col. 1:24 is one of many verses that shows this to be an ongoing process. St. Paul speaks of uniting his sufferings to the cross and thus participating in the work of redemption. No, Christ does not need our efforts, our works, our sufferings, but He CHOOSES to unite our efforts, as small as they are, to His supreme effort on the cross, and thus makes each of us His co-redeemers, His brothers, His cooperators, His co-heirs (Rom. 8:17). Christ is the vine and we are the branches, as Our Lord teaches us in John 15…as long as we abide in Him we are able to bear fruit that is pleasing to the Father. As St. John says in the first chapter of his gospel, to those who believe Christ gave the “power to become the sons of God” (John 1:12) and a share of His own divine nature (2 Peter 1:4).
I think this is an important foundation to cover before even diving into the issue of purgatory. Yes, we are indeed called to work out our salvation with “fear and trembling” (Phil. 2:12) for the Lord, through His death and resurrection, has won for us the grace that makes this possible. By ourselves we are nothing…our works are but empty rags…but united to His grace they become worthy of the Father’s approval.
It is for this reason that Our Lord, in Matthew 25 with the parable of the sheep and the goats, declares the righteous to be saved BECAUSE of their good works ("…for I was hungry and you fed me…") and the wicked damned BECAUSE of their lack of good works. Scripture is clear that salvation is by the grace of Christ alone. Scripture is also clear that salvation is by works. Christ Himself preaches it again and again without any qualification - Matthew 25 being a great example. Only the traditional Christian teaching, the faith of the Fathers for 1500 years, as testified to and lived by Catholics, Eastern Orthodox, Oriental Orthodox, and the Assyrian Church of the East, reconciles these apparent contradictions. It is Christ who enables us, by His transforming grace within our souls, to please the Father.