This brief verse of just five words is not a rhetorical pause, as it were, while James collects his thoughts before going on, having little or no connection with what has preceded it. Most commentators agree that it is a hinge verse reaching back to warn the reader concerning the error just discussed in verses 13-15, and opening the discussion which corrects that error in verses 17-18. As such, the verse holds the two paragraphs of this section together.
“Do not be deceived” (mē planasthe), warns James. This phrase occurs in several places in the New Testament, usually in contexts where the writer is warning his readers concerning serious errors which “strike at the heart of the faith itself” (Davids, 86). For example, Paul uses it in 1 Corinthians 6:9 and Galatians 6:7, in both cases warning the Christian community concerning the reality of divine judgement because of lifestyles which are incompatible with life in the kingdom of God. The phrase has a similar sense here: those who claim they are tempted by God (v. 13) are deceived; make no mistake, says James, sinful life arises from human lust and leads ultimately to death. This is neither God’s will nor God’s work. That James refers to his readers as “my beloved [brothers]” (adelphoi mou agapētoi)—the NRSV correctly omits “brothers” given adelphoi is inclusive of both genders—shows, however, that he does not consider that they have in fact fallen from their faith. They are still in the family, so to speak. But as a concerned and diligent pastor, he admonishes and warns them concerning the seriousness of the error that some, apparently, have fallen into.
Love for the congregation is necessary for effective pastoral ministry, especially when exhortation and admonition are required. That James uses the term for siblings also indicates that he addresses them not in the mode of a parental authority over them, but as one of them and alongside them. He wears his pastoral authority confidently but lightly.