when he comes to be glorified in his saints, and to be admired among all those who have believed (because our testimony to you was believed) in that day.
There are two purposes of the coming here cited, but these need not be considered as a total list.  Paul's use of "come" in this verse shows that the "revelation of Christ," spoken of a moment earlier, is the same as his "coming"; and, therefore, the various references to his revelation, his appearance and his coming all apply to the same event.