Because that which may be known of God is manifest in them; for God hath shewed it unto them.
Because that which may be known of God, х to (G3588) gnooston (G1110)]. Three senses have been put upon this expression:
(1) the known of God (so the Old Latin and Vulgate, DeWette, etc.);
(2) the knowable of God (so Erasmus, Calvin, Beza, Grotius, Tholuck, Stuart, Conybeare, Mehring, Green); (2) the knowable of God (so Erasmus, Calvin, Beza, Grotius, Tholuck, Stuart, Conybeare, Mehring, Green);
(3) the knowledge of God (as the Syriac, Chrysostom, Luther, Fritzsche).
The first and last of these senses, in the only sense of them which has much to recommend them, almost resolve themselves into the middle one-that of our own version, which we think decidedly the preferable. It is objected to this sense, that though in the classics it is the usual sense, yet the Septuagint and the New Testament use it in the sense, not of what may be, but of what is known. But besides that this as but partially true [see Romans 1:20, anapologeetous (G379), and Romans 2:1, anapologeetos (G379)], as the word is not very common anywhere, and the senses run into each other, we must be guided in each case solely by the context. It is further objected, that all which may be known of God is not "manifest" to the pagan; and therefore the sense cannot be 'that which may be,' but 'that which is known is manifest in them.' But the apostle does not say 'all that may be known,' But only "that which may be known;" and to show that he did not mean 'all,' he expressly specifies in the next verse what of God it was that they did know-namely, "his eternal power and Godhead." This, then, is what is manifest in them [en autois (G846)] - not 'among them' (as Erasmus, Grotius, Fritzsche), meaning what the pagan philosophers attained to by reflection, amidst the brutish ignorance of the mass of the people, but (as all the best interpreters take it) 'within them,' in the sense which the next verse will more fully explain.
For God hath showed it unto them, х efaneroosen (G5319)] - 'for God showed it unto them,' in the constitution stamped upon man's nature in his creation, in which the conviction of a God is deeply rooted, and through the perception of Him in the works of His hand resulting from this.