There is a school of thought, that all of our lives are already worked out beforehand, and God has already worked out who are going to Live and who are going to Die.
This is a scary thought, and quite rightly so: it contradicts all reason to assign Justice to God's being; the idea of a superficial “freedom of choice,” while He has already decided beforehand where one is going. So the worst of sinners may enter Heaven on account of “His grace”: while some of the greatest true saints, while living their lives according to every Word He gave, are damned, simply on account of His decision.
There is an opposing school of thought, that God left all decision on mankind's ending to themselves, and therefore one's actions and decisions dictate God's decisions, which influences where one ends up. This is another scary thought, for this indicates that the omnipotent, omniscient Creator of all has no control over the future, and literally takes a gamble, on whether or not mankind will obey His Word; adjusting Himself to mankind's whims and decisions, the Master becoming the slave and the King becoming the servant.
For those who believe the lie, that God exists to serve mankind (and this heresy has taken post in the modern teachings): Jesus Christ has become Man to serve his Father's will. He did what pleased the Father, not what pleased men. And His ultimate sign of obedience to God the Father, was to give His life as ransom for many (not all); for few shall follow where He has led, and few shall find the Way to Life and enter through the narrow gate.
His appearance to st. John on Patmos, was not at all that of a servant. He appeared as the Prince of Peace, ready to come to earth to take control and, with his faithful servants, prepare the earth over a thousand years for the coming of God the Father with New Jerusalem.
There is a third school of thought on the topic of “predestination”, which is rarely heard:
Since time is non-existent in eternity (even time shall end, indicating that it is part of the creation), it means that God is not limited to time. At all. Which means, He sees Creation Day 1, Judgment Day, and all days in-between, at once.
So He does not need to decide beforehand, who goes where. Mankind decides it on their own. God has mercy on whom He wills, for He wills to have mercy on all who obey His commandments. It is man's choice, not God's which eventually leads to God's Judgment for Life or for Death.
Simply put, God sees right now, the past, present and future. And He sees on creation day 1 already what man has decided four years from now.
So He does not need to be unjust, to have His chosen people. He chose them, based on their decisions. That is why He could say that He loved Jacob from the beginning, but hated Esau. One Worldly “blessing” and a moment of impatience...