Urban II is said to be the first to grant the first plenary indulgence for the crusades. However, it was unscriptural and more in line with the Islamic belief of jihad.
So you honestly believe that Indulgences came from Muslim jihad?
And references for that or just conjecture?
The Good Thief received an indulgence from the cross.
Protestants should follow his example, especially since he did the good work of defending Christ while he was on his own cross.