Anxiety can be sinful if it reflects a spirit of unbelief in the gracious promises of a heavenly Father. We must be careful, lest we heap upon tender consciences burdens they need not or cannot bear.
You are thinking of Christ’s command not to seek what you should eat or drink, nor to have an anxious mind (Luke 12:29), and Paul’s words: ‘Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God’ (Philippians 4:6). Don’t take away the force of these commands: Christ tells us not to be anxious – we should take that seriously.
Anxiety involves a troubling or tormenting fear about ‘what might be’, a sense of being left hanging. Speaking to Job, Zophar expressed ‘a turmoil within me’, a frantic or agitated spirit, with swirling thoughts and distressing doubts provoking speech (Job 20:2). This gives a good picture: the words ‘worry’, ‘care’, and ‘concern’ can all carry something of the same meaning.