God's foreknowledge is much, much more than a prior knowledge of what people will or will not do and be. Certainly, the Lord God does know from eternity all things about all people because he is omniscient - He knows all things. Nothing is hidden from God. Nothing takes him by surprise. God never learned anything. He just know. He is omniscient. But God's omniscience must never be confused with his foreknowledge. Omniscience is an attribute of God. Foreknowledge is an act of God.
GOD'S FOREKNOWLEDGE IS OF PERSONS, NOT THINGS. Paul does not say, "What he did foreknow," but "Whom he did foreknow!" God's foreknowledge of his elect is his everlasting love for them (Jer. 31:3). God knows his elect from eternity as he knows no one else (Matt. 7:23). He knows us in Christ with love and affection, took infinite pleasure and delight in us (Prov. 8:31), and found satisfaction with us (Eph. 1:6). God's foreknowledge is his special, distinguishing love for his own elect from eternity!
GOD'S FOREKNOWLEDGE IMPLIES HIS ETERNAL ELECTION AND OWNERSHIP OF HIS PEOPLE. We are "elect according to the foreknowledge of God" (I Pet. 1:2). When the Scriptures speak of God's knowledge in a special, distinctly gracious way, the implication is that God owns and approves of it (Psa. 1:6; John 10:14). So those whom God "foreknew" he owned as his people before the world began.
GOD'S FOREKNOWLEDGE CERTAINLY INVOLVES HIS FOREORDINATION OF HIS ELECT UNTO SALVATION AND ETERNAL LIFE IN CHRIST. It includes both determination and control. In fact, the word translated "foreknowledge" in I Peter 1:2 is translated "foreordained" in I Peter 1:20 (See Acts 2:23). As it relates to his purpose of grace, God's foreknowledge is his determination from eternity to save his elect. It is not God knowing what we would be, but what he would do (Acts 15:18).
GOD'S FOREKNOWLEDGE IS THE INFALLIBLE SECURITY OF HIS ELECT (II Tim. 2:19). Think of it - If you are a child of God by faith in Christ, you were known of God from eternity, one of those "whom he did foreknow!" God almighty, in amazing love and infinite grace, determined to save you before the world was made!