Ultimately, all orthodox Christians believe in predestination. Why? The term is in the Bible.
He chose us in Him before the foundation of the world, that we would be holy and blameless before Him. In love He predestined us to adoption as sons through Jesus Christ to Himself, according to the kind intention of His will (Eph 1:4-5).
The passage above is clear. God chose who He would save before we had any say in the matter and His choosing is kind. Now, there are only two ways to interpret this: God chose people irrespective to what they would choose on their own and this necessitates Him doing something kind to make them believers, or God was kind in making people blameless, but He did so knowing that the people He chose were the ones He foreknew would choose on their own.
Now, there are all sort of interpretative difficulties with the latter interpretation, namely Eph 2:8-10, Rom 9, Phil 1:29, and other Scriptures. Here is one of them from the text of Ecclesiastes:
Whatever exists has already been named, and it is known what man is; for he cannot dispute with Him who is stronger than he is (Ecc 6:10).
The idea in this passage is the same as Ephesians. God not only knows the future, He has ordained (“named”) every detail. However, how about the latter part of the passage? What does knowing what a man “is” mean? Well, in the words of Ecclesiastes:
Indeed,there is not a righteous man on earth who continually does good and who never sins (Ecc 7:20).
So, if everything that exists has already been decided, and that it is known that man is not righteous, man cannot dispute against God because He is “stronger.” Dispute about what? Clearly, God’s decision to harden him as punishment for his unrighteousness or to be gracious to Him and give him a new heart that follows God’s commandments.
Why? God can, because of His strength and God can do so blamelessly, due to man’s unrighteousness. The burden of proof that God chooses man because of his future choice to have faith seems to grow steeper. After all, whatever exists has already been named, not because God knew what man would do, but because He knows what man is.
We have already charged that both Jews and Greeks are all under sin; as it is written,
There is none righteous, not even one;
There is none who understands,
There is none who seeks for God;
All have turned aside, together they have become useless;
There is none who does good,
There is not even one (Rom 3:9-12).
A man like this cannot be chosen because of his future decisions, because his future decisions, knowing what a man is, will not be seeking God, but rather turning aside from Him. Rest assured, if you know this is not you and you desire to place your trust in Jesus Christ for the forgiveness of your sins, then indeed God has already begun a work in you and has decided to do so since the beginning.