A good starting point for this discussion is to contrast definitions of worry and concern from the Compact Edition of the Oxford English Dictionary. "Worry" is defined as "a troubled state of mind arising from the frets and cares of life; harassing anxiety or solicitude." While "concern," on the other hand is defined as "to distinguish, discern, or perceive." An interesting argument can be made, then, that concern for something without an element of worry suggests that we may be lacking in empathy. Does a degree of worry bring the seriousness and immediacy of a crisis into clearer focus? For example, doesn't worry encourage many a parent and grandparent to pray earnestly for adult children who may be on a spiritually dangerous path?
We multitaskers can worry about many different things at the same time! There's the worry CBS executives may have with regards to unbalanced talent like their notorious Charlie Sheen. We might broadly refer to this as an office worry. With regards to our salvation, there's the legitimate spiritual worry or concern that recognizes that our salvation is worked out with "fear and trembling" (Philippians 2:12). When we sin, after all, we are turning our backs on Christ. Our free will means that this separation from God and man may happen at any moment unless we walk with Christ. If worry is a symptom that we are "going it alone," we have committed a sin akin to idolatry, placing our faith in ourselves instead of Christ.
Then, there's the worry or anxiety that comes when we find ourselves facing something that represents a deep-seated fear or even phobia: heights, for instance. Sometimes we know that there's an element of the irrational in these worries, but, then again, perhaps at times even these fears may serve a legitimate purpose.
When I attended Seattle Pacific University in the late 1980s, I spent the summer of 1988 working at their Camp Casey Conference Center on Whidbey Island (across the choppy Admiralty Inlet from Port Townsend). I ended-up spending most of that summer painting roofs on my own, and, I have to tell you, I was always worried about falling--especially when the ladder crashed down in the wind when I was a couple stories up, but I digress... My point in bringing this up is that it seems to me that this kind of worry can serve a legitimate and natural purpose. Let's face it, I am a clumsy guy. Having a natural worry or anxiety associated with heights might just be the natural genetic compliment to that "clumsy gene." It's going to keep me from being a painter on the Golden Gate, and that's probably a good thing.
We're all familiar with the usual kinds of worry described above. We could refer to these as ordinary daily worry, but there's also worry which is rooted in physical illness or trauma. There is, for instance, anxiety in some people which is attributed to chemical imbalances in the brain. These people suffer dark feelings of worry and panic that most of the rest of us could not imagine. This kind of worry really is more along the lines of an illness than anything else.
So, here we've outlined some basic types or examples of worrying. The question remains unanswered, is worrying a sin? Archbishop Fulton Sheen said, “All worry is atheism, because it is a want of trust in God.” As an admirer of this great man, I have to admit that he makes a good point, but perhaps turning to a deeper understanding of what sin is will help us untangle this issue more clearly? Here's part of what the Catholic Encyclopedia offers on the question or nature of sin.
In every sinful act two things must be considered, the substance of the act and the want of rectitude or conformity (St. Thomas, I-II:72:1). The act is something positive. The sinner intends here and now to act in some determined matter, inordinately electing that particular good in defiance of God's law and the dictates of right reason. The deformity is not directly intended, nor is it involved in the act so far as this is physical, but in the act as coming from the will which has power over its acts and is capable of choosing this or that particular good contained within the scope of its adequate object, i.e. universal good (St. Thomas, "De malo", Q. 3, a. 2, ad 2um). God, the first cause of all reality, is the cause of the physical act as such, the free-will of the deformity (St. ThomasI-II:89:2; "De malo", 3:2). The evil act adequately considered has for its cause the free-will defectively electing some mutable good in place of the eternal good, God, and thus deviating from its true last end.
We see, then, that unless worry represents an intentional act for wrong born out of our own free will (a possibility perhaps if we "nurture" our worry), simple worry, while not being good thing, fails to rise to the seriousness of a sin. Philippians 4:6 urges us not to worry, but to place our faith in Christ. This verse offers a comfort to the reader that through faith in Christ, we may pray for relief of our fears and anxiety. The verse does not say that those who suffer from this particular emotion are committing a sin. For whatever reason, there are those who pray for healing of physical or mental illnesses--such as chronic worry or anxiety--but the answer from heaven is not always the miraculous healing for which we hope. Sometimes, these things must instead be born by the believer, to be offered up as a sacrifice to God.
One of the strongest arguments against painting all worry as sin is seen in passages such as the one describing Christ in the Garden of Gethsemane. As we read in the 26th chapter of Matthew or the 14th chapter of Mark, Christ himself is displaying anxiety or worry about what's to come. Does this mean that Christ committed a sin because He failed to trust His Father. Of course not! Christ, as all God and all man, suffered as we suffer. Since worry and anxiety represent an integral part of our existence since the Fall, He also experienced these feelings as a man. Another writer I was reading recently pointed out the good example of Christ staying behind in the Temple as a child. Do we really think that Mary and Joseph weren't worried about their son while they searched for him high and low?
Unless we nurture or kindle the flame of our worry, ignoring Christ and His message, I can't agree that ordinary worry constitutes a sin. Of course, this doesn't mean that worrying is a good thing; it's true that we should strive to replace worrying with devotion to and faith in Christ. It's important to offer some clear thinking on this particular issue. For instance, if one begins to believe that chronic worry or anxiety is a sin in and of itself, it creates a vicious circle, simply creating more worry about the worry. Besides being unhelpful, it's based on faulty, overly simplistic reasoning and an incorrect understanding of the nature of sin itself. In conclusion, here's how Catholic Answers' Michelle Arnold eloquently addresses this issue.