From The Openness of God:
Often God says things like this in the Bible: “Perhaps they will understand” or “It may be that they will listen.” From such phrases we must deduce that God has different options depending on people’s responses that are still outstanding (see Jer 26:3; Ezek 12:3; etc.). In saying “perhaps,” God also indicates that he does not possess complete knowledge of the future. The dozens of examples like this throughout Scripture establish that the Bible thinks of an open future that is not completely certain. The popular belief in God’s total omniscience is not so much a biblical idea as an old tradition.