Certain attitudes are indeed antithetical to the Christian life and our renewed mindset in Christ. Hatred, anger, and jealousy may be among the more obvious and commonly accepted to belong to the category of attitudes that the Christian ought to reject. Furthermore, these are typically unambiguous given the appropriate context. That is, while we may exhibit these qualities more often than we like, and while we understand that with God there is abundant forgiveness and mercy towards us despite these things, we never encounter a Scriptural exhortation along the lines of "Therefore, let us hate..." or "Therefore, let us be angry..." and so on and so forth. But what of fear? Many of us are quite familiar with St. John's beautiful statement that "There is no fear in love; but perfect love casts out fear, because fear involves punishment, and the one who fears is not perfected in love" (1 John 4:18). Is fear, then, never appropriate for the Christian? If we are, in and through Christ, drawn into a loving relationship with the Triune God, is any and every existence of fear a sign that we are not yet truly "perfected in love"? Can there be such thing as a healthy fear? The short answer to this last question, and one that I feel is warranted by Scripture, is "yes." A healthy fear can exist in the heart of a Christian who has been perfected in love and, therefore, is without fear. Now this of course sounds like a blatant contradiction, which is my intention. But, rather than stopping here and accepting it as such, perhaps we might be able to conclude that it is instead a paradox whose purpose is to thrust us upon the living God in whom we trust in love that is verily perfected without fear.
Now, I will assume that for the present purposes it is understood that the type of "fear" under discussion is not the more reverence-like "fear" as in "the fear of the LORD," which is, for example, "the beginning of wisdom" and "knowledge" (Psalm 111:10; Proverbs 1:7). Rather, the fear that I have in mind is closer to the concept of "being afraid" - and it is this type of fear that Christians are often discouraged from entertaining. And this is with good reason in many cases, but the questions we are undertaking are whether it is right to reject it wholesale, and what consequences may arise if we do or do not. Recall again the fact that we do not find exhortations to hatred or jealousy in Scripture. Instead, we encounter the exact opposite - we are called to love and not be jealous. And this latter point is similarly applied to fear, as we saw in 1 John 4:18. But, the seemingly odd thing is that we are actually called to fear in certain instances and contexts. For example:
[W]ork out your salvation with fear and trembling. (Philippians 2:12)
[C]onduct yourselves in fear during the time of your stay on earth. (1 Peter 1:17)
And, in addition to these, we find yet another explicit exhortation to fear in Hebrews: "Therefore, let us fear if, while a promise remains of entering His rest, any one of you may seem to have come short of it" (Hebrews 4:1). The unescapable reality that the writer of Hebrews urges us towards is that a healthy type and amount of fear will serve as a successful deterrent of "unbelief" that inhibits us from entering God's rest (3:19).
But how do we reconcile this with 1 John 4:18 and other plentiful examples in Scripture that teach us not to fear? The answer is, I believe, found in balance that comes from a living relationship of loving dependency upon God and His eternal faithfulness. We need to fear because we can deny Him; we need not fear because He cannot deny Himself (2 Timothy 2:11-13).
The truth that Christ's inability to deny Himself gives us cause not to fear is the express purpose of what John is writing in his first epistle. We can see this by expanding upon the immediate textual context. John writes:
Whoever confesses that Jesus is the Son of God, God abides in him, and he in God. We have come to know and have believed the love which God has for us. God is love, and the one who abides in love abides in God, and God abides in him. By this, love is perfected with us, so that we may have confidence in the day of judgment; because as He is, so also are we in this world. There is no fear in love; but perfect love casts out fear, because fear involves punishment, and the one who fears is not perfected in love. We love, because He first loved us. If someone says, "I love God," and hates his brother, he is a liar; for the one who does not love his brother whom he has seen, cannot love God whom he has not seen. And this commandment we have from Him, that the one who loves God should love his brother also. (1 John 4:15-21)
One of the main points that John conveys in this passage is that because of God's nature - perfect love- we abide in God and His love (and He in us) if we believe "the love which God has for us" by confessing His Son, Jesus. Therefore, "we may have confidence in the day of judgment" and need not ever fear that God will somehow fail to uphold His faithfulness - an ontological impossibility because it is likewise related to His immutability. But this confession of ours, as Hebrews clearly illustrates, is something that we "must hold fast" to, not because we are ultimately faithful, but because God is and ever will be (Hebrews 10:23; see also 2 Timothy 2:11-13; Hebrews 4:14). In the epistle to the Hebrews, the writer reminds us of those who fell in the wilderness because we are really no different than they in terms of the susceptibility to disbelieve and disobey. We must fear lest we become overly self-confident and not, therefore, utterly reliant upon the grace and faithfulness of God.
Still, as with many things, this can be taken too far and, if we do, it will be damaging to our spiritual health. Even in light of the aforementioned exhortations toward healthy fear, nowhere in Scripture are we expected to have our lives marked by an excessive state of fear that consumes our thought and, ultimately, our being. Excessive and unbridled fear borders upon denying the faithfulness of Christ and such fear indeed is "not perfected in love." The danger that results if we fear too much is that we fail to admit the reality of God's power to keep us unto salvation. The danger that results if we fear too little is that we fail to take into account the gravity of our sin and our potential to follow the example of the Israelites who fell in the wilderness. For the Christian, fear, even the healthy type (and, perhaps especially the healthy type), is a temporary attitude that, when exercised in a right and living relationship to the ever-faithful God actually keeps us closer to Him. Exercised properly, it keeps us mindful, when necessary, that in the present time a promise is open to enter God's rest, and we must "fear lest [... we] come short of it" (4:1). But we need only fear "while [the] promise remains," or, as St. Peter puts it "during the time of [our] stay on earth" (4:1; 1 Peter 1:17). In the life of the world to come, fear has neither place nor substantive meaning for those who have confessed the Son of God. In the interrum, however, it can indeed bind us closer to Christ and the promise of rest that we have through Him. And, if ever we are prone to take this further than we ought, we need only remember that the God and Father of our Lord Jesus Christ is indeed blessed, and:
[A]ccording to His great mercy [He] has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, to obtain an inheritance which is imperishable and undefiled and will not fade away, reserved in heaven for [us], who are protected by the power of God through faith for a salvation ready to be revealed at the last time. (1 Peter 1:3-5, emphasis added)
"He who began a good work in [us] will perfect it until the day of Christ Jesus" (Philippians 1:6). Fear is then to be had in light of the eternal and infinite faithfulness of God. Paradox? Maybe. Contradiction? No.