"Like," for most English-speaking humans, means like. I say that to clarify for those who may not be acquainted with the nuances of social media. When you “like” your wife’s cooking, it may simply mean that you don’t want to eat Cheerios for dinner tomorrow night. When you “like” your child’s latest painting, it may say speak more to your relationship with the child than it does the child’s artistic talent. But usually, like means like. And that’s especially true if, as with social media, you provide no context.
So when you “like” a photo of someone half naked at a public beach with his half-naked girlfriend, you are saying you “like” the situation he is depicting. “I meant I just like his smile,” someone says. Fine. Then write a comment — “Nice smile. Now put some clothes on.” Or, if you think that’s too rude, send a private message. But don’t tell everyone he knows that you approve of what he’s doing. That’s what a “like” does.
Since when did it become so important to spare someone’s feelings or offer unconditional friendship? Personally, I’d rather tell them the truth (Galatians 4:16) — especially when it may save their soul. The last thing I would want to do is pat someone on the head because they are doing something that takes them further away from God. Season your speech, certainly (Colossians 4:6). But don’t give someone diabetes with all the sugar coating.
Try this as a litmus test. If someone is depicting themselves doing something that may cost them their soul, imagine instead they are saying, “Hey, friends! I’m trying to sell my soul to Satan!” Then decide whether to hit the “like” button.