17 Therefore do not be unwise, but understand what the will of the Lord is.
Rather than foolishly missing opportunities that God affords us (v. 16), believers need to gain a good hold of the will of God.
do not be unwise,
“Unwise” here is a different Greek word than “fools” of verse 15. “Unwise” connotes the idea of being without reason. This person does not make wise use of his understanding. An unwise person is someone who does not seek God’s will and, because of this, does not see things in their true light. These people behave contrary to what is right.
but understand [comprehend] what the will of the Lord is.
The word “understand” is more than knowing the facts; the idea is to know the facts with perception. The fundamental thought of “understanding” is to bring together. An understanding person can put together the precept with the thing perceived. We understand the will of the Lord by reflective thinking on how principles of Scripture apply to experience. This is to function as a “wise” person. We need to see things as God sees them.
Christians apply God’s will to their experience as the standard of understanding and rule of conduct.
We find the general will of God in the Word of God; we find the specific will for an individual believer through the application of extant principles of the Word. We do not find this will through unadulterated experience, visions, or coincidence. We find His will through the correct use of our understanding.