In the quiet intimacy of the upper room, just hours before His arrest, Christ gave His disciples some final encouragement and instruction. He revealed again His unity with the Father, comforted His disciples with the promise of heaven, and told them about the Helper who would empower them for the work ahead (John 14:1-17). But as usual, the disciples failed to fully understand what He was saying.
Some of their confusion lives on in the church today. In particular, one of Christ’s statements in this passage has confounded and divided many believers, with some using the Lord’s promise as proof of the continuation of the apostolic gifts throughout the history of the church.
In John 14:12, Jesus promises His followers: “Truly, truly, I say to you, he who believes in Me, the works that I do, he will do also; and greater works than these he will do; because I go to the Father.”
In his book The Upper Room, John MacArthur explains why there is persistent confusion in the church today about the nature of Christ’s promise.
Christians over the centuries have wondered at the richness of such a promise. What does it mean? How could anyone do greater works than Jesus had done? He had healed people blind from birth, cast out the most powerful demons, and even raised Lazarus from the dead after four days in the grave. What could possibly be greater than those miracles?  John MacArthur, The Upper Room (The Woodlands, TX: Kress Biblical Resources, 2014) 93.
For charismatic authors who believe in the continuation of the apostolic gifts, the answer is simple. In his book Authentic Fire, Michael Brown explains it this way:
Jesus gave a universal promise in John 14:12 that implies that all believers can ask God to demonstrate His healing and miracle-working power through them, since the statement in John 14:12 is programmatic, as Jesus said: “Truly, truly, I say to you, whoever believes in me will also do the works that I do; and greater works than these will he do, because I am going to the Father.” How is this not universal in scope, given that the identical Greek phrase ho pisteuon eis eme, whoever believes in Me, is always universal in application in John? (See John 6:35; 7:38; 11:25; 12:44, 46.) And while we can debate exactly what Jesus intended by the “greater works,” it is difficult to escape from the conclusion that whoever believes in the Son will also perform miraculous signs, based on: 1) the immediate context (14:9-11, with the emphasis on miracles as the works done by Jesus); 2) the universality of the language used; and 3) the assurance which follows, guaranteeing the efficacy of prayer to the Father in Jesus’ name. . . .
This promise cannot be limited to the apostle based on the language of “whoever believes in Me,” nor can it [sic] limited to non-supernatural acts of service. The reverse is actually true.  Michael Brown, Authentic Fire (Lake Mary, FL: Excel Publishers, 2014) 188-189.
Writing for Charisma Magazine, charismatic author Larry Sparks makes the same assertion that Christ’s words to His disciples are “a powerful blanket statement” for all believers, throughout church history.
Whoever means whoever. This is beyond the 12 apostles and the 72 called-out ones in Luke 10. Whoever spans all generations. Whoever invites us, in the 21st century, to once again contend for an outpouring of supernatural power in our midst. http://www.charismamag.com/index.php/newsletters/spiritled-woman-e-magazine/23749-the-danger-of-celebrating-halloween
Bill Johnson, pastor of Bethel Church in Redding, California, (one of the most influential charismatic churches in the world) and instructor at the Bethel School of Supernatural Ministry, teaches a similar interpretation of the “greater works.” In his book When Heaven Invades Earth, he writes, “The miraculous is a large part of the plan of God for this world. And it is to come through the Church.”  Bill Johnson, When Heaven Invades Earth (Shippensburg, PA: Treasure House, 2003) 136. Johnson teaches that in His incarnation, Christ emptied Himself of all divine attributes, and in His humanity is the model for our lives.
Jesus became the model for all who would embrace the invitation to invade the impossible in His name. He performed miracles, wonders, and signs, as a man in right relationship to God . . . not as God. If He performed miracles because He was God, then they would be unattainable for us. But if He did them as a man, I am responsible to pursue His lifestyle.  When Heaven Invades Earth, 29.
Through that lens of Christ’s humanity, Johnson understands John 14:12 as a challenge to surpass His miraculous works.
Jesus’ prophecy of us doing greater works than He did has stirred the Church to look for some abstract meaning to this very simple statement. Many theologians seek to honor the works of Jesus as unattainable, which is religion, fathered by unbelief. It does not impress God to ignore what He promised under the guise of honoring the work of Jesus on the earth. Jesus’ statement is not that hard to understand. Greater means “greater.” And the works he referred to are signs and wonders. It will not be a disservice to Him to have a generation obey Him, and go beyond His own high-water mark. He showed us what one person could do who has the Spirit without measure. What could millions do? That was His point, and it became His prophecy.  When Heaven Invades Earth, 185.
We could go on and on with examples of that kind of teaching from charismatic sources, but you get the point. For those arguing for the continuation of the apostolic gifts, John 14:12 is a battleground text.
But was it really meant to be a promise of miraculous power to every believer? The testimony of church history suggests it was not, as many generations of saints have come and gone without any evidence of apostolic power. And while charismatics will argue that there is evidence of miracles today, it’s always anecdotal, rarely documented or objectively substantiated, and often comes from the far-flung corners of the globe.
Even by that flawed standard, the Spirit’s supposed miraculous work today is significantly different than His ministry through the apostles in the first-century church. Far from healing the crippled, curing the ravages of disease, and raising the dead, it seems the focus of the Holy Spirit’s healing ministry today is limited to rheumatoid arthritis, nagging back pain, and other subjective ailments. No longer is His work dramatic, obvious, and undeniable—today it’s mysterious, indiscriminate, and surprisingly absent when and where it’s most needed.
There is no arguing against the fact that Christ bestowed His supernatural power to His disciples (Acts 5:12-16). But there is no reason to characterize their miracles as “greater” than Christ’s, either in magnitude or degree. Furthermore, there is scant evidence that His promise of power extends to the subsequent generations of the church. In other words, not only have we not seen the charismatic interpretation validated by nearly 19 centuries of Christian history, it can’t even be validated by the miraculous works of the twelve apostles! (For further exegetical explanation of the limits of Christ’s promise in John 14:12, I recommend this article from Matt Waymeyer.)
So if Christ wasn’t promising miraculous power that exceeded His own, what did He mean by “greater works?” As John MacArthur explains, Jesus was indicating that the disciples works would be greater not in power, but in extent.
The key to understanding this promise is in the last phrase of verse 12: “because I go to the Father.” When Jesus went to the Father, He sent the Holy Spirit. The Spirit’s power completely transformed the disciples from a group of fearful, timid individuals into a cohesive force that reached the world with the gospel. The impact of their preaching exceeded even the impact of Jesus’ public teaching ministry during His lifetime. Jesus never preached outside a 175-mile radius extending from His birthplace. Within His lifetime, Europe never received word of the gospel. But under the ministry of the disciples the good news began to spread, and it’s still spreading today. Their works were greater than His, not in power, but in scope. Through the indwelling Holy Spirit, each one of those disciples had access to power in dimensions they did not previously have, even with the physical presence of Christ.
The disciples undoubtedly thought that without Christ they would be reduced to nothing. He was the source of their strength; how could they have power without Him? His promise was meant to ease those fears. If they felt secure in His presence, they would be even more secure, more powerful, able to do more, if He returned to the Father and sent the Holy Spirit.  The Upper Room, 93-94.
Christ did not hand-pick His disciples merely to perform signs and wonders in His name. They were chosen to extend the good news of His sacrificial, atoning death beyond the reaches of Israel and Palestine, to the far reaches of the globe. They were preaching the completed work of Christ on behalf of sinners, spawning spiritual revival throughout the known world. In that sense, their work was greater than Christ’s, as they bore witness to the truth of His life and death, and saw firsthand the transforming work of the Holy Spirit.
As John MacArthur explains, the work of the gospel is the greatest ministry work of all.
After all, the greatest miracle God can perform is salvation. Every time we introduce someone to faith in Jesus Christ, we are observers of the new birth; we are supporting the most important spiritual work in the world. How exciting it is to be involved in what God is doing spiritually and to do things greater than even Jesus saw in His day.  The Upper Room, 94.