I think you should mail them back to her with a little note attached.
Perhaps:
Dear Ruth,
In my travels I happened upon the magazines you left behind on the train. I can see you are working very hard to reach out to people to share the "good news". However I must warn you, Ruth, that your great efforts to share uplifting edification can sometimes backfire as the magazines might fall into the hands of those who do not appreciate the value of spiritual food. I very much enjoyed reading your magazines and will look forward to finding them again as I go about my way. Perhaps, if you have time, you might leave a few magazines at the local laudromat as I am also known to spend a good deal of time there as well as on the train. That would please me to no end! Please keep up the good work of sharing my favorite literature! I look forward to meeting you in person sometime. Perhaps even at the next assembly!
Warmest regards,
Satan