Was James writing to heaven-bound Christians in the first half of this chapter? Keep in mind that he previously addressed some who professed to be saved, but whose faith was void of works, proving them to be unsaved (2:14-17). I tend to think that same theme has surfaced once more in 4:1-10, and James was again addressing false or backslidden believers. Notice he said that they were guilty of murder (4:2). If he meant that literally, that proves they were unsaved. The New Testament declares that no murderer possesses eternal life (1 John 3:15). Borrowing an Old Testament metaphor, James also called them "adulteresses" because their friendship with the world made them enemies of the Lord (4:4), a sobering warning to modern worldly "Christians." It seems quite possible that at some point in the past those whom James was addressing were obedient followers, but if so, it is clear they had grossly backslidden. How can "enemies of God" be heaven-bound believers?
Obviously they can't, which is why James called them to repentance. His words in 4:7-10 are appropriate for an evangelist calling sinners to Christ: "Submit therefore to God. Resist the devil and he will flee from you. Draw near to God and He will draw near to you. Cleanse your hands, you sinners; and purify your hearts, you double-minded. Be miserable and mourn and weep; let your laughter be turned into mourning, and your joy to gloom. Humble yourselves in the presence of the Lord, and He will exalt you."
But what about James' words in this passage about God jealously desiring "the Spirit which He has made to dwell in us" (4:5)? This could well be a warning to those who return to loving the world---spiritual adulterers---of the possibility of losing the Spirit within them whom God "jealously desires." Still, grace was available to those who would repent.
Beginning in 4:11, James turns his attention to the "brethren." And he again borrows a theme found in Jesus' Sermon on the Mount, that of passing judgment. Like Jesus, James was referring to the sin of speaking evil of a fellow believer, a sin that is especially grievous when it is committed by someone with a "log in his own eye." As we learned when we studied Jesus' words on the same subject, we are not forbidden from making moral appraisals of other people (and clearly, James was doing that very thing throughout his letter). We absolutely must appraise other people morally if we are going to obey Jesus' commandments not to "give what is holy to dogs" and not "throw our pearls before swine" (Matt. 7:6). And we must appraise people if we are going to identify and avoid false prophets (Matt. 7:15). This passage in James must also be balanced with other scriptures such as 3 John 9-10 and Galatians 2:11-14, which teach that sometimes it is proper to expose a person's sins publicly in order that hypocrisy might be exposed or that others might be protected.
In any case, we need to be extremely cautious that we don't put ourselves in God's place of Judge, speaking evil of a genuine believer. If you've ever been a victim of evil speaking, you know how it hurts, especially when there is more to the story than what is being told.
Is it wrong to make future plans according to James 4:13-17? No, but it is presumptuous and boastful to talk about what we are intending to do without acknowledging the Lord's rule. We can do only what God permits, and since we are "just a vapor that appears for a little while and then vanishes away" (4:14), we may not be around tomorrow. Yesterday, more than 150,000 people died on planet Earth. How many thought they would be alive today? They would have benefitted from James' words. How wise it is to pray like David:
Who understands the power of Thine anger, and Thy fury, according to the fear that is due Thee? Teach us to number our days, that we may present to Thee a heart of wisdom (Ps. 90:11-12).