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.
Instead of τοις πιστευουσιν, them that believe, τοις πιστευσασιν, them that have believed, is the reading of ABCDEF, many others, the later Syriac, Slavonic, Vulgate, and Itala, with most of the Greek fathers. This reading is undoubtedly genuine.