“Neither the theif has heard any of His teaching, nor did the Roman guard, who being Roman also didn’t know the Old Testament.”
And how do you know that?
Luke 23:39-43, “ And one of the malefactors which were hanged railed on him, saying, If thou be Christ, save thyself and us. But the other answering rebuked him, saying, Dost not thou fear God, seeing thou art in the same condemnation? And we indeed justly; for we receive the due reward of our deeds: but this man hath done nothing amiss. And he said unto Jesus, Lord, remember me when thou comest into thy kingdom. And Jesus said unto him, Verily I say unto thee, To day shalt thou be with me in paradise.”
Mark 15:39, “And when the centurion, which stood over against him, saw that he so cried out, and gave up the ghost, he said, Truly this man was the Son of God.”
Both knew who he was so they must have had some knowledge of the scriptures to know him as “Lord” his “kingdom” and “Son of God” and his message.
The term "Lord" does not exclusively mean God in the Bible. The Son of God is a title given to angels and kings. It does not have the Christian meaning.
The thief on the cross could have been pulling Pascal's wager, since he had nothing to lose.
Jesus did not go to paradise on that day, and what would he do in paadise?
This is also contrary to Luke's obvious belief in Hades/Sheol (Luke 16:19-31), rather than paradise. Then seven chapters later he believes in paradise!? And he is telling us that God went to paradise on that day? Yet they alos tell us Christ didn't even resurrect for three days.