As St. Thomas teaches, the duty to correct doesn't bind if there's not a reasonable chance that they'll accept the correction (among other conditions). In this case, they'll probably just irately shred the material. It's not as if they haven't already heard that this is wrong. On one level, they know it's wrong and are rejecting natural law. On another level, they probably just don't care anymore. Prayer and penance are about the best you can do for them.