If you are worried that you are engaging in slacktivism by posting a cartoon as your Facebook profile pic to oppose child abuse, just remember that it’s not slacktivism, it’s broadcasting a cause preference that can be mobilized.
You should only feel guilty if this action represents a decrease in your engagement on this issue (for example, if you changed your pic instead of voluteering at a children’s home). For most people, this will be an incremental increase in their engagement on this issue, and thus a good thing.