Theophylact of Ohrid — on Rom 1:4 (Commentary on Romans)

“Above he said: "concerning His Son," and now he proves how He was known as the Son of God, and says that He was declared, that is, shown, established, recognized; for declaration is recognition itself, a verdict and decision. For all recognized and decided that He is the Son of God. How so? "In power," that is, through the power of signs which He performed. Moreover, "according to the Spirit of holiness," through which He sanctified believers; for to grant this is proper to God. Also "through the resurrection from the dead," for He was the first, and moreover He alone raised Himself. Thus, He was known and revealed as the Son of God through the resurrection; for this too is a great thing, as He Himself says: "When you have lifted up the Son of Man, then you will know that I am He" (Jn. 8:28).”