You are a Christian because God has ordained it

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Earnestly Contending For The Faith That Was Once Delivered To The Saints

Now, God's sovereign. Of course, He—He knows, “He is not willing that any should perish but all might come to repentance.” But in order to be God, He has to know, and He does know before the thing ever come to pass, who would be saved and who would not be saved. That's right.
So there is some people that will not, and God knew it in the beginning they would not. And He even raised up Pharaoh and hardened his heart for that very cause, that He might show His power. And Esau and Jacob, to show the election of God might stand sure… Before either child was—when they were born, 'fore they were born, God said, “I love Jacob and hate Esau.” That's right. Before…
See, you're a Christian because God has ordained that you must be a Christian. Now, you can turn it aside. Some… God will set somebody in your place. But your place is setting there. If God calls you, go take it and stay with it.

Daily Bread II Peter 1:10
...give diligence to make your calling and election sure: for if ye do these things, ye shall never fall.