I just had a glance at it and once of his arguments there is obviously wrong, which we can see from context. He says that he that speaks in tongues edifies himself means it 'puffs your ego.'
But look at Paul's argument in I Corinthians 14.
3 But he that prophesieth speaketh unto men to edification, and exhortation, and comfort.
4 He that speaketh in an unknown tongue edifieth himself; but he that prophesieth edifieth the church.
John MacArthur, at least back in the early 1990's, would have had us believe that 'edify' in verse 3 is good, but edify in verse 4 is bad? Why the definition change between verses?
5 I would that ye all spake with tongues but rather that ye prophesied: for greater is he that prophesieth than he that speaketh with tongues, except he interpret, that the church may receive edifying.
Consider the argument, "He that speaks in a tongue edifies himself...I want you all to speak with tongues." If speaking in tongues puffs up the ego, why would Paul want them to do it? In verse 5 speaking in tongues, even without an interpreter is a good thing. We know this because Paul wanted them to speak with tongues. But prophesying is better.
Edifying self--> Good.
Edifying church--> Better.
The one who prophesies and edifies the church is greater than the one who speaks in tongues (without interpretation) and edifies himself. Compare with what Jesus said that He who is the greatest among you shall be the servant of all.
Anyway, MacArthur's assertions do not line up with the text. Basically, he wants to redefine 'edify' between verses 3 and 4, and we are supposed to believe it, I suppose, because he says so. And then the next verse does not make sense if you follow his argument.
His Liberal Oracle of Delphi Interpretation
These days, John MacArthur is known for verse-by-verse teaching. But here, he does not do that. His interpretation does not hold up if you actually go verse by verse through the text. What he's doing is parroting the ideas of 19th century liberals about speaking in tongues. His argument only makes sense if you do not believe the scripture is authoritative and you believe that Paul missed it. Some of the liberals thought the Corinthians were engaging in pagan babble. But if we look at Paul's writings, he treats I Corinthians 14 tongues as a genuine gift. He says their tongues were a 'fabrication coming from their pagan background' and a counterfeit.
Now, if you don't really believe the text of the passage is inspired, you might think Paul was just wrong, and that the Corinthians were engaging in some nonsense pagan babbling. But you can't approach the text sensibly and go verse by verse with a coherent interpetation and believe that if you have a high view of scripture. I think MacArthur was reading some bad commentaries and parroting what he'd read.
Using the Oracle of Delphi as an exegetical key makes no sense either. They were a bit of a distance from Delphi. And what evidence is there for the Oracle of Delphi speaking in some kind of magical babble? There were myths about some people not being able to understand what the prophecy meant, but where is the evidence for it being some sort of incomprehensibl language? Plutarch was a first century author, and he was actually a priest at Delphi. He actually addressed the issue that many people expected a prophecy in high poetry at Delphi. He defended the idea that the oracle could give a prophecy in regular prose. So it is clear they were speaking comprehensible words at Delphi, even if the prophecies they gave were inegmatic.
The really sad thing here is this man is so anti-speaking in tongues, that he has actually attacked the speaking in tongues in the actual pages of scripture itself.