If God calls us, then why do we have to accept Jesus?

Ephesians 1:5 says that God predestined us to Himself before the world. If this is true that we have already been chosen, then what purpose does an "altar call" serve, where people come forward to "accept" Christ?

The Bible teaches that saving faith is a product of God’s work in the heart of a sinner. The Lord by His Spirit brings faith to a person’s heart according to His mercy, as Paul says:

Rom. 9:15 For He says to Moses, “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.”
Rom. 9:16 So then it does not depend on the man who wills or the man who runs, but on God who has mercy.
Rom. 9:17 For the Scripture says to Pharaoh, “For this very purpose I raised you up, to demonstrate My power in you, and that My name might be proclaimed throughout the whole earth.”
Rom. 9:18 So then He has mercy on whom He desires, and He hardens whom He desires.

Nevertheless, Jesus does call sinners to repent:

Mark 1:14 Now after John had been taken into custody, Jesus came into Galilee, preaching the gospel of God,
Mark 1:15 and saying, “The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel.”

And the apostles echoed this call in their personal ministry of evangelism. As Paul said:

Acts 17:30 “Therefore having overlooked the times of ignorance, God is now declaring to men that all people everywhere should repent,
Acts 17:31 because He has fixed a day in which He will judge the world in righteousness through a Man whom He has appointed, having furnished proof to all men by raising Him from the dead.”

God works through the call of the Gospel to lead men and women to confess His name, yet the very prompting for that confession is God’s Spirit working in the heart. Therefore, God’s call to repent gives opportunity for God’s gift of faith to be revealed in the heart of a sinner and God’s name to be glorified for His grace.