“Greater Works” in John 14:12
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.
Charismatics often use this passage as proof that we ought to expect miracles worked by human hands.
And shall do greater works than these. Many are perplexed by the statement of Christ, that the Apostles would do greater works than he had done. . . . First, we must understand what Christ means; namely, that the power by which he proves himself to be the Son of God, is so far from being confined to his bodily presence, that it must be clearly demonstrated by many and striking proofs, when he is absent. Now the ascension of Christ was soon afterwards followed by a wonderful conversion of the world, in which the Divinity of Christ was more powerfully displayed than while he dwelt among men. Thus, we see that the proof of his Divinity was not confined to the person of Christ, but was diffused through the whole body of the Church.
—John Calvin, Calvin’s Commentaries Volume XVIII (Baker Books, 2009), Commentary on the Gospel according to John, 2:89–90.
Those “greater works” are the miracle of regeneration through the preaching of the gospel on a scale the world had never seen before.
See also J. C. Ryle and John MacArthur on this passage.