Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world (Heb. 1:1-2)
Πολυμερῶς καὶ πολυτρόπως πάλαι ὁ θεὸς λαλήσας τοῖς πατράσιν ἐν τοῖς προφήταις ἐπ᾽ ἐσχάτου τῶν ἡμερῶν τούτων ἐλάλησεν ἡμῖν ἐν υἱῷ, ὃν ἔθηκεν κληρονόμον πάντων, δι᾽ οὗ καὶ ἐποίησεν τοὺς αἰῶνας (Heb 1:1-2 BGT)
Although the light of nature, and the works of creation and providence do so far manifest the goodness, wisdom, and power of God, as to leave men unexcusable; yet are they not sufficient to give that knowledge of God, and of His will, which is necessary unto salvation. Therefore it pleased the Lord, at sundry times, and in divers manners, to reveal Himself, and to declare that His will unto His Church; and afterwards for the better preserving and propagating of the truth, and for the more sure establishment and comfort of the Church against the corruption of the flesh, and the malice of Satan and of the world, to commit the same wholly unto writing; which makes the Holy Scripture to be most necessary; those former ways of God's revealing His will unto His people being now ceased (Heb. 1:1-2). — The Westminster Confession of Faith 1646, Chapter I, Paragraph I
Cessationism has fallen on hard times in many areas of the church. This is very unfortunate however, as the very basics of the Reformed faith is predicated on an important truth taught by Scripture itself - the cessation of extra-biblical revelation itself.
Heb. 1:1-2 is probably the strongest passage on the issue, which is incidentally also the proof-text for the last part of the Westminster Confession Chapter I, Paragraph I. As Heb. 1:1-2 states, God has spoken to us now in His Son. God's revelation in Christ is the final revelation which abrogates all previous means of revelation which includes dreams, visions, revelation through the mouths of prophets etc. All of the diverse means of revelation found in the Old Testament have now disappeared with the revelation in God's Son Jesus Christ.
Therefore, all such "sign-gifts" have ceased, having being part of the inferior things that are passing away. No more should we expect God to communicate His will to us through dreams and visions and signs. The Son has come, so why should we go back to the types and shadows of the Old Covenant?
In speaking of a new covenant, he makes the first one obsolete. And what is becoming obsolete and growing old is ready to vanish away. (Heb. 8:13)
The Charismatics by their lust after signs and wonders and the sign-gifts are turning towards these things that are passing away. Instead of seeing the sign gifts as those given for a season, they assume that they know why the Spirit gives the gifts He does give, instead of seeking the wisdom of the Spirit in knowing why He gives what He gives when He does give them. They turn the Holy Spirit into a spiritual vending machine where we are warned not to "grieve the Spirit" and thus "seek the greater gifts," yet all of such is done with no concern at all over the true intent and purposes of the Holy Spirit, as if the Holy Spirit must work the same way as He did worked in Corinth 2000 years ago.
Scripture however has the final say. In THESE LAST DAYS, God has spoken to us in His Son. NOT in dreams and visions and prophecies falsely-called. Not in "words of knowledge," "impressions from the Spirit," or the latest "apostle" in town. We would do well to heed the final Word of Scripture than to pay heed to the wisdom of the "spiritual men" with their "words from God."
So why do I call myself a Cessationist? I do so because it is better to obey God than the subjective claims of men. As Luther said about the Anabaptist Thomas Müntzer, we shouldn't trust such men even if they have swallowed the Holy Spirit "feathers and all." Let God be true, and every man a liar. Amen.