The concept of being created in the image of God is at the center point of many Christian anthropological positions (anthropology is the study of humanity: what makes humans human). My pastor often says that you should never create a doctrine around a single verse. This is an excellent rule of thumb, and I highly recommend it. But, ironically, when we are talking about being made in the image of God, we have to deal with the fact that this term is actually only used in one passage of all of Scripture: Genesis 1:26-30 (though referenced elsewhere). However, this is a rather important verse. It is specifically the creation of man, and as such gives us what I think is a legitimate exception to the general rule.
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