What was the abundance of revelations that Paul received?
The abundance of revelations was God unveiling to Paul the doctrines of grace, the Gospel, and church-age teachings, and also giving him a glimpse of glory. Because such revelations could exalt him, God gave him a thorn in the flesh, a messenger of Satan, to buffet him and keep him humble.
Les explains that the abundance of revelations first included the revelations of the doctrines of grace, the Gospel, and the church-age teachings. That alone was enough, but Paul also received a glimpse of glory, a revelation, leaving him bursting with all this. To keep him from being exalted, getting the big head, or becoming proud, God gave him a thorn in the flesh—the messenger or angel of Satan—to buffet or attack him, lest he be exalted above measure. The Greek, Les notes, makes it stronger: it was like being crucified, a constant pain, as if he was constantly suffering crucifixion.
And lest I should be exalted above measure through the abundance of the revelations, there was given to me a thorn in the flesh, the messenger of Satan to buffet me, lest I should be exalted above measure.