I would guess almost every Catholic who witnesses to his Faith has heard something akin to this I received from a Protestant Christian just the other day:
You Catholics fail to even consider the words of our Lord on the cross when he said, “It is finished” in John 19:30. In those few words Jesus declared for all ages that he accomplished everything necessary for our salvation on the cross. It is finished! For our part, all we are asked to do is believe in what he did for us. In adding a priesthood, sacrifice, good works—and all the other things Catholics say we must do—to our Lord’s simple words, the Catholic Church effectively denies the efficacy of what Christ did on the cross.
I would suggest three essential points in response:
First, the Catholic should agree with his Protestant interlocutor when it comes to the sufficiency of Christ’s sacrifice on Calvary. The Catholic Church acknowledges Christ’s sacrifice, and his sacrifice alone, to be of infinite value, and therefore able to appease the infinite justice of God. Or, as St. John tells us:
… we have an advocate with the Father, Jesus Christ the righteous; and he is the expiation for our sins, and not for ours only but also for the sins of the whole world (I John 2:1-2).
The real question centers on how God willed for the fruits of that infinitely meritorious sacrifice to be communicated and applied to the lives of his people. This involves more than Christ’s sacrifice alone by divine design. More on that below:
Second, the idea that “[Jesus] accomplished everything that was necessary for our salvation on the cross,” in a strict sense anyway, is not what John 19:30 or the Bible in general teaches. If we examine the context leading up to this statement of our Lord, for example, we find Jesus to have already explained precisely what he claimed to have “finished.” On Holy Thursday—the day before he was to be crucified—in his famous high priestly prayer to the Father for all of humanity, Jesus prayed:
I glorified you on earth, having accomplished the work which you gave me to do; and now, Father, glorify me in your own presence with the glory which I had with you before the world was made (John 17:4-5).
Jesus says he “finished” everything the Father gave him to do on earth. In no way did he say there was and is nothing left both for him and mankind to do at all for salvation.
Third, the Bible provides a litany of examples of the fact that both Jesus and we have much more to accomplish for our salvation when Jesus said, “It is Finished.”
Jesus Had More to Do
St. Paul obviously did not believe there was nothing left at all for Jesus to accomplish for our salvation/justification after Calvary because in Romans 4:25 he said:
Jesus… was put to death for our trespasses and raised for our justification.
Obviously, Jesus had not been “raised” from the dead yet when he said “it is finished.”
The inspired author of Hebrews tells us Christ would also continue to “save those who draw near to God” until the end of time through his high priestly ministry at the right hand of the Father:
But [Christ] holds his priesthood permanently, because he continues for ever. Consequently he is able for all time to save those who draw near to God through him, since he always lives to make intercession for them (7:24-25; see also Heb. 8:3; I Tim. 2:5).
And clearly Jesus still had to send the Holy Spirit in order that the world might be saved.
“He who believes in me, as the scripture has said, `Out of his heart shall flow rivers of living water.'” Now this he said about the Spirit, which those who believed in him were to receive; for as yet the Spirit had not been given, because Jesus was not yet glorified (John 7:38-39).
“But you shall receive power when the Holy Spirit has come upon you…” And when he had said this, as they were looking on, he was lifted up, and a cloud took him out of their sight (Acts 1:8-9).
When the day of Pentecost had come, they were all together in one place… And they were all filled with the Holy Spirit… (Acts 2:1-4)
In him you also, who have heard the word of truth, the gospel of your salvation, and have believed in him, were sealed with the promised Holy Spirit, which is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory (Eph. 1:13-14).
He saved us, not because of deeds done by us in righteousness, but in virtue of his own mercy, by the washing of regeneration and renewal in the Holy Spirit, which he poured out upon us richly through Jesus Christ our Savior, so that we might be justified by his grace and become heirs in hope of eternal life (Titus 3:5-7).
We Have More to Do
If you noticed above, I was careful to say Christ did not accomplish everything needed for man’s salvation on the cross in a strict sense. The Bible and the Catholic Church do teach Christians can be said to be saved/justified by grace alone in the sense that it is God alone, and therefore, God’s grace alone, that is the first cause of our salvation (cf. Titus 3:5-7; Eph. 2:8-9). So, in that sense, we can say “Jesus did it all for us” though not just on the cross, but by his entire life, death, burial, resurrection, and priestly ministry at the right hand of the Father (cf. CCC 517).
But when it comes to the application of those merits into the lives of real human beings, the Bible makes it equally clear that we are also “justified by works,” “obedience,” our “words,” our “faithful[ness],” and more. All of this on man’s end must be empowered by God’s grace in order to be meritorious before God, but in examining just some few of these texts we could consider below, we will discover in Scripture just what we find in CCC 2010:
Since the initiative belongs to God in the order of grace, no one can merit the initial grace of forgiveness and justification, at the beginning of conversion. Moved by the Holy Spirit and by charity, we can then merit for ourselves and for others the graces needed for our sanctification, for the increase of grace and charity, and for the attainment of eternal life.
We will focus on “merit[ing] for ourselves” in this brief post. “Merit… for others” will be for another time and another post.
We Must Contribute to Our Own Justification Before God
You see that a man is justified by works and not by faith alone (James 2:24).
Do you not know that if you yield yourselves to anyone as obedient slaves, you are slaves of the one whom you obey, either of sin, which leads to death, or of obedience, which leads to righteousness (Gr. – eis dikaiosunein – “leads to justification”). (Romans 6:16)
I tell you, on the day of judgment men will render account for every careless word they utter; for by your words you will be justified, and by your words you will be condemned” (Matt. 12:36-37).
For it is not the hearers of the law who are righteous before God, but the doers of the law who will be justified (Romans 2:14).
We Must Be Faithful and Obey Christ
…you will be hated by all for my name’s sake. But he who endures to the end will be saved (Matt. 10:22).
Be faithful unto death, and I will give you the crown of life (Rev. 2:10).
… but if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin… If we confess our sins, he is faithful and just, and will forgive our sins and cleanse us from all unrighteousness (I John 1:7-9).
And do not fear those who kill the body but cannot kill the soul; rather fear him who can destroy both soul and body in hell… So everyone who acknowledges me before men, I also will acknowledge before my Father who is in heaven; but whoever denies me before men, I also will deny before my Father who is in heaven (Matt. 10:28-33).
Space does not permit us to include the enormous numbers of biblical texts mandating for our salvation manifold things that we must do. We must “repent” (Acts 2:38; 3:19; Mark 1:15; II Cor. 7:8-10), be baptized (John 3:3-5; Romans 6:3-4; I Peter 3:21; Acts 22:16; Mark 16:16), persevere in obedience (Gal. 6:7-9; Romans 2:6-7; Acts 5:32; Heb. 5:8-9; II Tim. 2:12; John 15:1-6), keep the commandments (Matt. 19:16; I Cor. 7:19), and more.
In fact, Jesus makes this about as clear as can be in Matt. 5:44-45:
But I say to you, Love your enemies and pray for those who persecute you, so that you may be sons of your Father who is in heaven.
According to Jesus, you have to do something, e.g., “love your enemies and pray for those who persecute you,” not just to demonstrate that you are “a son of your Father;” rather, “so that you may be,” or “so that you may become (Gr. – genesthe) a son of your Father.”
One thing is abundantly clear: Jesus did not mean there is nothing else necessary for salvation when he said the famous words “it is finished.” So let’s get to work and “work out [our] salvation with fear and trembling!” (Phil. 2:12)