"passion" and "passionate"
What does "passion" and "passionate" mean in the title of these two books? Do they refer to sufferings and troubles or enthusiasm? Because "passion" in "Christ’s Passion" certainly means sufferings.

Frans Masereel, created the first two such graphic narratives, "25 Images of a Man's Passion" in 1918 and "Passionate Journey" in 1919, a few years before the first expressionist films were produced. Both titles of Masereel’s early books refer to medieval forms of narrative (versions of Christ’s Passion and Books of Hours)...

Question

"passion" and "passionate"
What does "passion" and "passionate" mean in the title of these two books? Do they refer to sufferings and troubles or enthusiasm? Because "passion" in "Christ’s Passion" certainly means sufferings.

Frans Masereel, created the first two such graphic narratives, "25 Images of a Man's Passion" in 1918 and "Passionate Journey" in 1919, a few years before the first expressionist films were produced. Both titles of Masereel’s early books refer to medieval forms of narrative (versions of Christ’s Passion and Books of Hours)...

Answer

You're right that the spiritual meaning of "passion" is "suffering", directly from the Latin.  The adjective, like you say is "passionate" but I have never heard it used in connection with the meaning of "passion" as "suffering".  Given what you say about the content of both books and the fact that the author is the same, it is quite likely that "passionate" here has the meaning of "relating to suffering".

Unless you made the religious context really clear, nowadays, people would automatically think that "passionate" meant "enthusiastic, committed etc" or alternatively "amorous, romantic".