If you want to have a go at Dispensationalism, then you need to be prepared to account for a number of eschatological topics and their (assumed necessary) relationship with each other. (You also need to be ready to deal with questions of interpretative approach, but that’s a different ballgame). For example, if you start an eschatological discussion with a Dispy, you are bound to be asked about (at the very least): Daniel’s 70 weeks, the focus of Matthew 24-25, the (so-called) “rapture”, the (so-called) “millennium”, the (so-called) “great tribulation” and when it occurs, the “great white throne of judgment”, the (supposed) battle of Armageddon… you get the idea.
In some ways, it can be overwhelming and even exhausting to get through this type of discussion simply because of the tangled web of ideas and theology that Dispensationalism has weaved. Thus, instead of going at the thing whole-hog and dismantling Dispensationalism in toto (quite frankly: you’d have an easier time convincing a Jehovah’s Witness that “Jehovah” is not even a word), it’s better to examine the individual parts and discern their respective validity. The one I want to focus on in this post is the so-called, “Restrainer” in 2Thess 2.6. Here is a more or less standard (Dispensational) approach to this issue:
Our identification of the Restrainer must ultimately be determined by the question, What person is able to hold back the efforts of Satan? To effectively counteract and restrain the personal activities of Satan demands a person, and one that is more than human. Only a supernatural person can truly frustrate the supernatural workings of Satan. This would at once rule out human agencies as well as all evil supernatural agents.
–D. Edmond Hiebert, The Thessalonian Epistles: A Commentary (1971), 313
The stuff that follows Hiebert’s question is understandable and, in the main, a reasonable conclusion. And a number of scholars (mostly Dispensational) contend that only the work/power/person of the Holy Spirit fits the needed criteria to restrain Satan. However, there are serious theological problems with seeing the (so-called) “restrainer” as the Holy Spirit, but I will have to side-step that conversation for now. I will simply echo John Chrysostom who said: “if [Paul] meant to say the Spirit, he would not have spoken obscurely, but plainly” (NPNF 1.13: 388).
My issue is that there is a more fundamental problem with Hiebert’s argument. Despite the understandableness and even the reasonableness of Hiebert’s observations, all of it ultimately relies on a bad or faulty premise–namely: 2Thess 2.6 is in fact talking about “the Restrainer”, and this (supernatural) person can be identified. To put it more bluntly: the legitimacy of his question and the proposed conclusion are dependent upon the validity of the presupposition that drives his question and conclusion. Without the presupposition, his argument falls flat at best or becomes meaningless at worst.
I am working on a longer treatment of this discussion, so if you want the details: please be patient. Until then, I will summarize things by saying: 1) the identity of “the Restrainer” in 2Thess 2.6 is not as clear-cut or obvious as Hiebert (and his fellow Dispys) believe, and 2) the rendering “the Restrainer” is not the only option for how one can translate the Greek verb, κατεχω (especially in the light of grammar and syntax). With regard to the first point, a number of suggestions have been made throughout the history of interpretation; the Holy Spirit is only one of those. In other words, we cannot (as Hiebert and his Dispy friends have done) conclusively assert unambiguously or unequivocally that Paul is talking about the Holy Spirit in 2Thess 2.6.
With regard to the second point, in terms of Greek grammar and syntax, κατεχω does mean “restrain” (or “hold back”), but only when it is accompanied by an object. At this point, Hiebert and his Dispy buddies seem to be vindicated because nearly every English translation of the passage mentions a “him” as the recipient (i.e. the object) of the Restrainer’s efforts. However, this vindication is valid only if we rely on English translations. Things change when we look to the original Greek text. In the Greek of 2Thess 2.6, there is no object associated with κατεχω. And in terms of Greek grammar and syntax, when this happens κατεχω means “prevail” (or “rule”). And just in case Hiebert et al think I’m being overly pedantic or liberally inventive, this intransitive use of κατεχω is not without support in Greek literature.
Now, those holding to a “Restrainer” interpretation might come back at me and say: “Ah, well, you see, you’re forgetting one of the cardinal rules of interpretation, which is to allow Scripture to interpret Scripture. In every other instance of κατεχω in the NT, it means ‘restrain’ or ‘hold back.’ Thus, when we use ‘restrain’ or ‘hold back’ in 2Thess 2.6, we’re simply following Scriptural precedent.” To which I would respond: “Fine, but you not only become guilty of committing the ‘illegitimate totality transfer’ fallacy; you also fail to recognize that the other instances where κατεχω appears in the NT, it has an object associated with it. Thus, the translation ‘restrain’ or ‘hold back’ in those cases is appropriate. But 2Thess 2.6 is completely unlike those other instances for one simple reason: it has no object.”
I would think Paul, being a fairly educated man, would be aware of the transitive and intransitive uses in Greek and the differences in meaning they convey. Moreover, the intransitive use of κατεχω (and the switch from neuter in 2.6 to masculine in 2.7) does better justice to Paul’s argument in 2Thess 2.3-10. In other words: the “mystery of lawlessness” (neuter) is what now prevails, as illustrated in 2.3-4, but which is currently unseen for what it truly is; and the “man of lawlessness” (masculine) is the one in charge of what prevails, and the one who will be revealed/exposed and defeated at the end, as noted in 2.8-10. This reading also prevents really wild and wicked views about the Holy Spirit and his role in salvation–views that I cannot, in good conscience (let alone academic integrity) support or even entertain.
 See e.g. L.S. Chafer, “Dispensationalism,” (1936): 428; E.S. English, Re-Thinking the Rapture (1970), 70-71; R. Gundry, The Church and the Tribulation (1973), 125-28; J. Walvoord, The Holy Spirit (1977), 115; R.L. Thomas, “1, 2 Thessalonians,” (1978), 325; M. Rosenthal, Pre-Wrath Rapture of the Church (1990), 257-61; C.E. Powell, “The Identity of the ‘Restrainer’,” (1997): 327. Cf. also C. Ryrie, First and Second Thessalonians (2001), 114-16.
 R.L. Thomas tries to wiggle out of this by claiming (without any support whatsoever): “It appears that to katechon (“what is holding back”) was well known at Thessalonica as a title for the Holy Spirit on whom the readers had come to depend in their personal attempts to combat lawlessness” (“1, 2 Thessalonians” , 325).
 Here I am relying on the arguments of C. Wannamaker, The Epistles to the Thessalonians (1990), 250-54 and J. Weatherly, 1 & 2 Thessalonians (1996), 258-62.
 See e.g. Thucydides, Peloponnesian War, 1.10, 3.89; Andocides, Speeches, 1.130; Aristotle, Politics, 1307b; idem, Meteorology, 345a; Lysias, Speeches, 3.42; Aristophanes, Ecclesiazusae, 434; cf. Homeric Hymns, 2.126; Herodotus, Histories, 7.188; Polybius, Histories, 1.25.7; Plutarch, Lives: Theaseus, 21; Sophocles, Philoctetes, 221; Euripides, Heracleidae, 83; idem, Helen, 1206; idem, Cyclops: Odysseus, 223; Antiphon, Speeches, 5.21.
 See J. Barr, The Semantics of Biblical Language (1961).