The Bible teaches predestination. Christians differ in their understanding of what it means, but no one who takes the Bible seriously can deny that the Scriptures teach it.
Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places, even as he chose us in him before the foundation of the world, that we should be holy and blameless before him. In love he predestined us for adoption as sons through Jesus Christ, according to the purpose of his will, to the praise of his glorious grace, with which he has blessed us in the Beloved. In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will (Ephesians 1:3-6, 11, my highlights).
This truth is meant to bring great glory to Christ. It is intended to humble us and bring us to our knees in gratitude. God’s grace has come to us based entirely on His own will and plan, and not because of anything we could or would ever do.
But sometimes the truth of God’s electing purposes may cause believers to question their own salvation. A sensitive conscience may ask, What if I’m not one of the “chosen ones?” I believe in Jesus, I love Him and want to follow Him. But what if He doesn’t love or receive me?
The Lord Jesus actually answered this. All that the Father gives me will come to me, and whoever comes to me I will never cast out. John 6:37, ESV
The Savior’s answer has two parts. First, He emphasizes God's sovereignty: All that the Father gives to me will come to me…Here we marvel, we bow, and we simply trust. God will have His way, a way He decreed before the foundation of the world.
But the second part of Jesus’ answer is about God’s comfort: whoever comes to me I will never cast out. How grateful we must be for the kindness of our Savior in saying this.
If you love Jesus, if your heart leaps when you hear His name, if you trust Him as your Savior, He will never cast you out. Your faith, your humility, and even your worry about this question, are evidences of God’s gracious choice.
The last stanza of that great old hymn “How Firm a Foundation” says the same thing:
The soul that on Jesus has learned for reposeI will not, I will not desert to its foes;That soul, though all hell should endeavor to shake,I’ll never, no never, no never forsake.