Good works can qualify us for salvation, and that thief was an example of someone who did good works, he didn't just believe in Jesus his acts where also good, his speech and his actions showed his goods works.
The bible says faith without work is dead(james 2 vs 17). And we see that this thief didn't just have faith, he also had works, how can a thief believe in someone who was being hanged? Everything should have made him like the other thief but he chose to have faith, despite all the circumstances his faith still stand string.
We are to work out our faith (Philippians 2:12 ), we shouldn't leave it to chance.
Be blessed as you watch the video below