Ask yourself brethren in Christ, just when did Christ’s apostles choose to follow Lord Jesus? When did they see Jesus, and say to themselves, “I think I’ll get up from fishing and go follow that man preaching over there”? When did apostle Paul choose to follow Jesus, as it certainly was not when Saul (Paul as a Pharisee) was on his way to hunt down Christians and bring them back to Jerusalem for trial?
In Lord Jesus’ prayer of John 17, He revealed that The Father had previously owned His apostles, and that The Father gave them to Jesus, and not only that, but that His apostles, like Jesus, were not of this world. They were ‘sent’, which is the meaning of the Greek word for apostle. But most of all, they were ‘chosen’ by Christ, which makes that ownership unmistakable.
Then with the examples Jesus gave of those who are not chosen, but reveal a certain level of Faith, we see much of Paul’s Epistles and even Lord Jesus giving warning to not fall away, but to make one’s ‘calling’ sure. This then points to those who are ‘called’ only, but are not ‘chosen’ sent ones like Christ’s apostles. This distinction is also covered in Lord Jesus’ prayer of John 17 (See John 17:6-21).
What then can one say about the free will of Christ’s ‘chosen’ ones? It’s actually very simple per the Bible Scripture examples. If they stray, Jesus will intervene with them to get them back on track of their duty they were chosen for. Apostle Paul is one of the greatest Scripture examples of this. Jonah is another. Jonah even went to the extreme of trying to use his own free will to commit suicide to keep from carrying out the duty God had assigned him to go preach to the city Nineveh. And when Jonah did obey God and preached to them, he sat on a hill overlooking the city of Nineveh in anger, because God saved the city by Jonah’s preaching God’s Word to them.
With apostle Paul, Lord Jesus directly intervened striking Paul blind on his way to Damascus to hunt down Christians. Jesus said Paul was His “chosen vessel” (Acts 9).
But the ‘called’ only, can… use their free will and fall away from the Faith IF… they so choose. The ‘called’ are here in this world to make their ‘choice’ using their free will. Only when they choose The Father and The Son will He intervene in their lives, as they become joined with His ‘chosen’ elect.
This also means, and it is specifically a danger for the times we are in now, being so close to the end of this present world, is the falling away to the coming pseudo-Christ or false-Messiah that God is allowing to appear in today’s Jerusalem working great signs and wonders with playing The Christ. (See 2 Thessalonians 2, and Matthew 24:23-24). That will be the main deception coming upon the whole world for the coming time of “great tribulation”. And we, Christ’s Church, will be here through it all.
Now the question of just ‘when’ God chose His sent apostles is another subject that one will go around in circles with if they don’t stay in the written Word of God, but stray to men’s theology.