Romans 1:19

“Because that which may be known of God, etc..] There are some things which could not be known of God by the light of nature; as a trinity of persons in the Godhead; the knowledge of God in Christ as Mediator; the God-man and Mediator Jesus Christ; his incarnation, sufferings, death, and resurrection; the will of God to save sinners by a crucified Jesus; the several peculiar doctrines of the Gospel, particularly the resurrection of the dead, and the manner of worshipping of God with acceptance: but then there are some things which may be known of God, without a revelation. Adam had a perfect knowledge of him; and his sons, though fallen, even the very Heathens have some notion of him, as that…”

“Because that which may be--rather, "which is." known of God is manifest in them; for God hath showed it unto them--The sense of this pregnant statement the apostle proceeds to unfold in Rom 1:20.”

“Because - The apostle proceeds to show how it was that the pagan hindered the truth by their iniquity. This he does by showing that the truth might be known by the works of creation; and that nothing but their iniquity prevented it. That which may be known of God - That which is “knowable” concerning God. The expression implies that there may be many things concerning God which cannot be known. But there are also many things which may be ascertained. Such are his existence, and many of his attributes, his power, and wisdom, and justice, etc. The object of the apostle was not to say that every thing pertaining to God could be known by them, or that they could have as clear a view of him as if…”

“For what is to be known of God - Those great principles which are indispensably necessary to be known. Is manifest in them; for God hath showed it to them - By the light which enlightens every man that cometh into the world. Romans 1:20”

“that which: Rom 1:20; Psa 19:1-6; Isa 40:26; Jer 10:10-13; Act 14:16, Act 17:23-30 in them: or, to them for God: Joh 1:9 Romans 1:20”