(15) See then that ye walk circumspectly, not as fools, but as wise,
(16) Redeeming the time, because the days are evil.
(17) Wherefore be ye not unwise, but understanding what the will of the Lord is.
We already understand that we must walk wisely and redeem the time. Beyond that, though, we are to understand the will of the Lord - what it is. How do we know God's will? We must redeem the time and instead of seeking after this world's ideas, seek first God and His kingdom.
1 Peter 2:13-16 - Submit yourselves to every ordinance of man for the Lord's sake: whether it be to the king, as supreme Or unto governors, as unto them that are sent by him for the punishment of evildoers, and for the praise of them that do well. For so is the will of God, that with well doing ye may put to silence the ignorance of foolish men: As free, and not using your liberty for a cloke of maliciousness, but as the servants of God.
Specifically speaking, God's will is that we submit to those in authority - in modern, American terms, to our president, governors, and police officers.
1 Peter 3:17 - For it is better, if the will of God be so, that ye suffer for well doing, than for evil doing.
God's will is not that we should suffer for our evil-doing (it is not His will that we should do evil), but it is possible that it is God's will for us to suffer, even if we are doing well in His eyes (think of Joseph who was cast into prison for his stand on purity - which, as we saw in 1 Thessalonians 4:3-6, is definitely the will of God).
1 Peter 4:1-5 - Forasmuch then as Christ hath suffered for us in the flesh, arm yourselves likewise with the same mind: for he that hath suffered in the flesh hath ceased from sin; That he no longer should live the rest of his time in the flesh to the lusts of men, but to the will of God. For the time past of our life may suffice us to have wrought the will of the Gentiles, when we walked in lasciviousness, lusts, excess of wine, revellings, banquetings, and abominable idolatries: Wherein they think it strange that ye run not with them to the same excess of riot, speaking evil of you: Who shall give account to him that is ready to judge the quick and the dead.
God's intent for Christ's suffering was that we would live according to His will. This passage outlines that there are two wills battling - the will of God, and the will of the Gentiles (i.e. the world). The will of the world is completely opposite to the will of God. We cannot follow the will of the world and be following the will of God at the same time.
1 Peter 4:19 - Wherefore let them that suffer according to the will of God commit the keeping of their souls to him in well doing, as unto a faithful Creator.
If it is in God's will for us to suffer, our responsibility is simply to commit the keeping of our souls to God. It seems as if one of the ways to do this is by continuing our well-doing.
1 John 2:17 - And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever.
The will of God (salvation for men) will be rewarded with eternal life. However, the will of this world simply fades away and is destroyed. Which will would we follow?