Searcher:
Actually, it kind of depends on how the context is interpreted. Some commentators see "the lawless one" as a coming individual, "the Antichrist." With that viewpoint, they see "the lie" as relating to verse 4 where he 'proclaims himself to be God.' (ESV) The NWT has, "publicly showing himself to be a god." Either translation is viable since "publicly showing" can mean "to show by argument, to demonstrate, prove." Thus, effectively "proclaiming." "God" or "a god" is also possible, although, at least in English, you would get a somewhat different connotation from each.
The Bible Knowledge Commentary says, "'The Lie' is the claim that the man of lawlessness is God." Similarly, The New Linguistic and Exegetical Key to the Greek NT says, "[the dative] Article [referring to "the"] may refer back to the claim of deity by the Antichrist."
For reference, here is verse 4 from the NWT and ESV:
(2 Thes 2:4 NWT) . . .He is set in opposition and lifts himself up over everyone who is called "god" or an object of reverence, so that he sits down in the temple of The God, publicly showing himself to be a god.
(2Thes 2:4 ESV) who opposes and exalts himself against every so-called god or object of worship, so that he takes his seat in the temple of God, proclaiming himself to be God
Some take "the lie" in the same way they take "the truth," which phrase is scattered about in the context. "The truth," as Paul uses it, doesn't mean any one particular fact, but rather a whole body of beliefs, even a lifestyle. From that, "the lie" could also be taken as the "lying signs and portents" (vs.9), and "every unrighteous deception" (vs.10), as well as "an operation of error" (vs.11), all of these collectively. (Or, "an operation of error" may be explanatory, describing the "lying signs and portents" as a whole.)
For reference, here is vv.9-12:
(2 Thessalonians 2:9-12 NWT) . . .But the lawless one's presence is according to the operation of Satan with every powerful work and lying signs and portents 10 and with every unrighteous deception for those who are perishing, as a retribution because they did not accept the love of the truth that they might be saved. 11 So that is why God lets an operation of error go to them, that they may get to believing the lie, 12 in order that they all may be judged because they did not believe the truth but took pleasure in unrighteousness.
Since the context is speaking of "those who are perishing," a whole group collectively, particular individuals may or may not be taken in by any particular aspects of "the lie" (when "the lie" is seen in this way).
Personally (your milage may vary), I prefer this latter application because in the context, "the operation of error," meaning all "the lying signs and portents" is for "a retribution." Its purpose in God allowing it (vs.11) is to expose those who "did not accept the love of the truth," or "believe the truth," "but took pleasure in unrighteousness." I don't think one particular lie could accomplish that end. In this view, "the lie" is a means by which God makes a clear demarcation between those being saved and those not. He simply uses Satan and "the man of lawlessness" towards that end.
Take Care
