Romans 4:17 - Matthew Poole's English Annotations on the Holy Bible

Before him whom he believed; i.e. in the sight or esteem of God. He was not the father of many nations by carnal generation in the sight of men, but by spiritual cognation in the sight of God. Or, as it may be read, like unto God, after his example; and then the meaning is, that God so honoured Abraham's faith, that he made him a father, in some respects like himself. As God is a universal Father, not of one, but of all nations, so was Abraham. Again, as God is their spiritual Father, not by carnal generation, so was Abraham also. Even God, who quickeneth the dead, and calleth those things which be not as though they were; i.e. Abraham believed in him as omnipotent. His omnipotency is described by two great effects of it. The one in making that to have a being again, which had ceased to be, as in the resurrection. The other, in causing that to be which never was; or to make all things of nothing, as in the creation: he expresseth this by calling things, to intimate the great facility of this work to God: he only spoke, and it was done; he commanded, and all was created. And as Abraham thus generally believed the power of God, so it is likely he made a particular application of it to his own state at present; as he believed that God could raise the dead, so, that he could raise him seed out of his own dead body, and Sarah's dead womb. And as he believed that God could create things out of nothing, so, that he could give him seed that had none; yea, and make the Gentiles a people that were not a people.