The word athemitos occurs twice in the New Testament. The first time, in Acts 10:28, it is rendered as “unlawful thing.” 1 Peter 4:3 contains the word also, where it is translated as abominable.
In the former instance, Peter uses the word to describe how it had been “unlawful” for Jews to keep close company with Gentiles, but now that God had removed the barrier between the two, we should accept His will in it. But to get a sense of this word, we have to know that Jew/Gentile table fellowship prior to the time when Christ declared all foods clean would not just have been something that would have made the Jew guilty of an infraction. It was the kind of “unlawful” that would have grossed him out — it would have been abominable.
Abominable actions of a moral nature are in view in the passage in 1 Peter 4. Back before a man was converted, he may have walked in the “will of the Gentiles,” which was orgiastic living — lust, licence, drunkenness, out-of-control parties, and abominable idolatries.
One of the differences between a moralistic man and a moral man can be seen here. A moralistic man disapproves because he has to, and secretly wishes he could have a piece of the action. A moral man doesn’t object in the same way at all. A moralistic man sees pornography as an orgy without him in it. A moral man reacts to pornography as an attempt to get up an appetite by watching people chew with their mouths open.