In all things give thanks, for this is the desirous will of God in Christ Jesus unto you, 1 Thessalonians 5:18.
Thanksgiving is an attitude of gratitude. It is a result of being Spiritual—when a grace believer is seeking out and emanating the things of the Spirit of God.
The lack of gratitude among humans leads to a rejection of who God is, resulting in men who think themselves wise but become futile in their reasoning, for their foolish hearts are darkened by hardness. They exchange the proper opinion of the incorruptible God for that of corruptible man, birds, four-footed animals, and creeping things. Following after their own uncleanness, they dishonor themselves among themselves and exchange the truth for the lie—independence from God.
As sons, we are to train our senses to distinguish what is proper from what is wrong, so that we may discern the desirous will of God for us in every situation of life. This mindset produces an attitude of gratitude in all things, for all things, and for all men, because our mind is set on the truth, and therefore we see things as they truly are.