So is your position.
He predestines some, he hardens hearts, but He doesn't prevent people from accepting His freely given grace.
Exactly. God does not prevent anyone from accepting his grace or following him or anything else having to do with one's salvation.
So did the 'good thief' make a choice on his cross to accept Christ?
Yes he did. He was called and God's grace was extended to him. For him, it was irresistible grace. For the other thieves either they were not granted grace or the grace they were granted was not irresistible.
He was saved because of his choice.
That would make him his own Savior. He was saved because of Christ. If it were up to him, then he, like the other thieves would have mocked and rejected Christ.
Tell me, was the grace you were given resistible or irresistible?
Since you came to the Lord, would you not have to agree that whatever Grace you were given was the irresistible kind?
I don't know. If I am one who was predestined, it would be irresitable. But just as people can reject God's grace, they can accept it.
And no, my choice does not make me my own savior. Like Paul, "I am redeemed by the blood of Christ, I trust in him alone for my salvation, and, as Scripture teaches, I am ‘working out my salvation in fear and trembling’ (Phil. 2:12), knowing that it is God’s freely given gift of grace that is working in me."
God does not prevent anyone from accepting his grace or following him or anything else having to do with one's salvation.
You are not making sense! You say he has predestined many to hell, so God prevents them from accepting His grace!