The omniscience of God is mind-boggling for many believers.
It’s not that God doesn’t want us to understand: He definitely does. All through scripture, He gives us everything we need to know about who He is and what He does. For those who are diligent in their studies, there will come a time somewhere down the line that the “light” finally comes on and we begin to accept God’s omniscience by faith. Sometimes, this may take a number of years of struggling over certain passages.
One particularly difficult passage to understand in regard to God’s omniscience is found in Romans Chapter 9. In this chapter, Paul is addressing the Jews and trying to explain to them that the covenant made with Abraham and God still exists for them. In fact, it still exists even today. He further explains that the Jews as a nation have rejected Jesus as Messiah and as a result of that rejection God is extending salvation to the Gentiles as well.
At one point in Chapter 9, Paul explains how God, in His omniscience, knew this rejection would take place and yet He “endured with much patience vessels of wrath prepared for destruction.” Most probably, God is referring here to unbelievers. Before even the beginning of time, God knew who would–and who would not–believe in Jesus; and He prepared a place in heaven for those who He knew would come to believe. Paul goes on to say that God did this “to make known the riches of His glory upon the vessels of mercy which He prepared beforehand for glory.” These vessels of mercy undoubtedly are the people that God, through His omniscience, knew would accept Jesus as the Messiah and believe on His name. And because God knew that, He prepared them beforehand for glory.
God’s omniscience allows Him to know—even before the beginning of time—which decision each created person will make when offered the choice of receiving and believing in Christ, or not. He is prepared for whatever happens in either choice. As believers, we accept on faith that God gives us the choice but that He knows the answer in advance.
The simple truth is God would never choose one and reject the other. His is a level playing field of fairness and justice.