There are at least two kinds of completion connected with Christians. One is the completion of whatever the Lord has given them to do and the other is the completion of the work of God in them. As to the first we can see the thought exemplified in Christ, but not I believe the second, as Christ was always full of grace and truth, having the divine nature absolutely.
Dealing with work for the Lord, we find that Christ said: “My food is that I should do the will of him that has sent me, and that I should finish his work” (John 4:34). It is not till we come to John 17 that Christ says: “I have completed the work which thou gavest me that I should do it” (verse 4).When Christ was speaking to his Father in this passage he had completed his preaching and teaching ministry, but He still had the work of atonement before Him . This was rather a matter of submission and endurance than an active work on his part (Philippians 2:8; Hebrews 12:2). As to this He said on the cross when He was about to die: “It is finished” (John 19:30). Some may think that what Christ said in John 17 just quoted included in Christ’s mind the atonement and I have no objection to this thought. In saying what He did maybe Christ was including in anticipation what He suffered on the cross. Other statements in John 17 such as: “And now I come to thee” (verse 13) are apparently anticipative. Everything in Christ’s life was timed accurately. Until He had completed his ministry He did not go to the cross. Before that time had arrived it could be said: “his hour had not yet come” (John 7:30).
As to the apostles, Christ instructed them as to the work they should do, thus we have for examples: “Matthew 28:19 and John 20:21-23". Paul was also given a commission: “Acts 13:2". However the time came when they had finished their work. Peter could say: “knowing that the putting off of my tabernacle is speedily [to take place], as also our Lord Jesus Christ has manifested to me” (2 Peter 1:14). Paul also could say similarly in Acts 20:24 and 2 Timothy 4:6-8.
We now have to consider our own position. That we are not Christ or indeed one of his apostles is obvious, but in our own measure we should be serving Christ whilst we are here on earth.“Ye serve the Lord Christ” (Colossians 3:24). We do not want to end our lives saying something like the one who was reputed to have said: “I am not afraid to die, but I am ashamed to die”. He was a believer but his service here for the Lord had been minimal. Even the dying thief testified to his fellow malefactor (Luke 23:39-43). Further, if we start a work for the Lord we should be concerned that we finish it. Christ speaks of this in Luke 14:28-30. Mark had put his hand to the plough but then went back, which in Paul’s eyes disqualified him for service on the next trip (Acts 13:5 and 13; 15:37/38). Compare Luke 9:62. We do not want to be like the the assembly of whom the Lord had to say:”I have not found thy works complete before my God” (Revelation 3:2). Our works, if done for the Lord, are important and it is said in Revelation 14:13 of some that their works follow with them. Paul speaks of our work being tried in fire and some persons receiving a reward and some not (1 Corinthians 3:12-15). For those of us who are, naturally speaking, nearing the end of our sojourn here on earth, it is a challenge as to how we have been spending our time. I have heard it said that if we retire from secular employment at 60 we then have more time to devote our energies to the Lord’s things. However, all of us need to number our days, that we may acquire a wise heart (Psalm 90:12).
Dealing with God’s work in us, one would mention that though Christ, unlike us did not need a work to be done in Him, He did learn things such as obedience (Hebrews 5:8 and Philippian 2:5-11). Not that He was disobedient and had to be taught to be obedient. Rather, until He took upon Himself the place of subjection, He had no personal experience of being obedient and learnt practically here what it entailed.
As to ourselves, there is tendency with some to think that because we have placed our trust in Christ’s finished work on the cross and therefore are confident that there is a place reserved in heaven for us (1 Peter 1:4) there is nothing further to be wrought in us. This is a mistake. That we have been made fit for sharing the portion of the saints in light is true (Colossians 1:12). If it were not so our place in heaven would be in doubt. However, there is another side to the matter. Paul says: “he who has begun in you a good work will complete it unto Jesus Christ’s day” (Philippians 1:6). Christ has done all that is necessary for us to secure us a place in glory, but a work in us has to be completed to perfect us for the place reserved for us (consider Philippians 3 particularly verses 8 to 14). That God works in us is true, but that does not mean that there is not to be movement on our part. As many have noticed, John Bunyan’s pilgrims were in movement. Christian had to reach the Cross but he did not stay there but moved on. (I have, incidentally, stayed in a house next to the cross thought to have been in the mind of John Bunyan when he penned the Pilgrim’s Progress) We need to grow spiritually else we may remain diminutive, that is, as children. While here we have the opportunity of growing. There is nothing in Scripture to suggest that we will grow when we are in heaven.
There are plenty of Scriptures to support the thought that we should make progress in our spiritual life. Paul speaks of God’s word, which also works in you who believe (1 Thessalonians 2:13). Then in 2 Corinthians 7:1 he says: “let us purify ourselves... perfecting holiness in God’s fear”. Note: Paul includes himself in this. In Ephesians Paul also speaks of the perfecting of the saints (chapter 4 verses 10 to 16). Christ Himself spoke of every one being perfected in Luke chapter 6 verse 40. Further, Peter speaks of the need to go on and not forget the purging of former sins (2 Peter 1:5-11). If one may refer to the types, those that entered the tabernacle in the wilderness had first to pass the brazen altar, but there was also the laver to be passed which qualified the priests to enter the holy place where was the candlestick, the altar of incense and the table of showbread. This led to the holy of holies where was the Ark of the covenant which represented Christ. In this dispensation all Christians are priests and have access to the holy of holies (1 Peter 2:1-10; Hebrews 10:19-22). In Nehemiah we have the gates to the city of Jerusalem spoken of. The first gate repaired was the sheep gate which points to the sacrifice of Christ, but there were other gates and there are other things to be learnt from these (chapter 3).
Other Scriptures could be referred to but one I think will suffice here. Paul writes of Epaphras praying that the saints might stand perfect and complete in all the will of God (Colossians 4:12). There is also the warning side. Paul says to the Galatians: “Are ye so senseless? having begun in Spirit, are ye going to be made perfect in flesh?” (Galatians 3:3) We need to consider both the warning as well as the positive side. King Saul in the Old Testament is really an example of one who took things up in the flesh and went either too far or not far enough and acted either too soon or too late. It is matter that could well be searched out. The fact that we are usually left here on earth after conversion is, on the one hand to be a testimony to others and, on the other that God’s work may be completed in us.
Note: As to New Birth it is usually taken to refer to what happens on conversion, that is, when we turn from darkness to light (Acts 26:18). This is because natural birth is an initial thing. However, in 1 Peter 1:23 we have the thought of “being born again” spoken of as a work in Christians, rather than an event in the past. New Birth is being born of God (John 1:13) and he that is born of God does not sin (1 John 5:18), but I have yet to find anyone who is marked by sinless perfection. However, after death we shall no longer have the flesh to contend with. All that we will then have morally will be what we are as born of God and a corresponding body.