Among those sins most exquisitely fitted to injure the soul and destroy the testimony, few can equal the sin of complaining. Yet the habit is so widespread that we hardly notice it among us. The complaining heart never lacks for occasion. It can always find reason enough to be unhappy. The object of its censure may be almost anything: the weather, the church, the difficulties of the way, other Christians, or even God Himself. A complaining Christian puts himself in a position morally untenable. The simple logic of his professed discipleship is against him with an unanswerable argument. Its reasoning runs like this: First, he is a Christian because he chose to be. There are no conscripts in the army of God. He is, therefore, in the awkward position of complaining against the very conditions he brought himself into by his own free choice. Secondly, he can quit any time he desires. No Christian wears a chain on his leg. Yet he still continues on, grumbling as he goes; and for such conduct he has no defense.
Do everything without complaining or arguing, so that you may become blameless and pure, children of God without fault in a crooked and depraved generation. Philippians 2:14–15
The cause for complaint is often a God-given opportunity for growth and praise. What at first appear to be thorns may prove to be divine prods that move us closer to God.
Deliver me from complaining, Lord. Rather, teach me to praise You and thank You for the opportunities to grow.