Let’s look again at Philippians…
4:4 Rejoice in the Lord always: again I will say, Rejoice.
4:5 Let your forbearance be known unto all men. The Lord is at hand.
4:6 In nothing be anxious; but in everything by prayer and supplication with thanksgiving let your requests be made known unto God.
4:7 And the peace of God, which passeth all understanding, shall guard your hearts and your thoughts in Christ Jesus.
4:8 Finally, brethren, whatsoever things are true, whatsoever things are honorable, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things. ASV
In this passage are many imperatives (commands). It does not say “Well, do your best.”. It says “be not anxious about anything.”. It is a very basic sentence that speaks volumes. In fact I think it is one of the biggest statements of faith in the Bible. It is telling us to deny our eyes and trust in the Lord in every single itty bitty or huge thing in our lives.
Jesus also said not to worry, that it was useless. Matthew 6:25-34. If Jesus said not to do it, then that really means not to do it.
6:25 Therefore I say unto you, be not anxious for your life, what ye shall eat, or what ye shall drink; nor yet for your body, what ye shall put on. Is not the life more than the food, and the body than the raiment?
6:26 Behold the birds of the heaven, that they sow not, neither do they reap, nor gather into barns; and your heavenly Father feedeth them. Are not ye of much more value then they?
6:27 And which of you by being anxious can add one cubit unto the measure of his life?
6:28 And why are ye anxious concerning raiment? Consider the lilies of the field, how they grow; they toil not, neither do they spin:
6:29 yet I say unto you, that even Solomon in all his glory was not arrayed like one of these.
6:30 But if God doth so clothe the grass of the field, which to-day is, and to-morrow is cast into the oven, [shall he] not much more [clothe] you, O ye of little faith?
6:31 Be not therefore anxious, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed?
6:32 For after all these things do the Gentiles seek; for your heavenly Father knoweth that ye have need of all these things.
6:33 But seek ye first his kingdom, and his righteousness; and all these things shall be added unto you.
6:34 Be not therefore anxious for the morrow: for the morrow will be anxious for itself. Sufficient unto the day is the evil thereof. ASV
Now, does that mean anxiety, worry, fretting is a sin? Well, to me, if the Lord says “don’t do it” and you do it, then it is a sin. So if He tells me “do not be anxious”, and I am, then it is a sin.