Paul here contrasts a foolish lifestyle with a wise way of living and says that it is important that we make a wise use of time and are also self-controlled concerning alcohol. We would all agree that wisdom is an essential aspect of a Christian outlook. Wisdom is not the same as being informed or as possessing intellectual abilities. It means the ability or discernment to do not only what is right but also what is best, based on the information one has.
The Bible in many places urges us to ask God for wisdom. In this passage, we are told about two aspects of walking in wisdom – our use of time and our self-control.
Concerning time, Paul says that the days are evil, and our response may be to want to become detached from them, to opt out. One does not have to enter a monastery in order to become a monk. What does it mean to make the best use of time?
Paul is using the illustration of purchasing a slave (which is why older translations had 'redeem the time'). While he did not approve of the practice of slavery, he realised that it could teach spiritual lessons, with the most obvious one being his frequent references to Christians as slaves of Jesus Christ.
We have to redeem the time that we have, which means that we have to be selective, choosing always the best option. Jonathan Edwards is famous for many things, one of them being a set of resolutions he put together to govern his life. When he was twenty he resolved ‘never to lose one moment of time, but to improve it in the most profitable way that I possibly can’. It is important to remember that each opportunity only comes once.
Linked to redeeming the time is Paul’s emphasis on self-control, seen in his rebuke of those who drink too much wine. But we will miss the point of the reference if we conclude that Paul is only speaking about wine. What he is saying is that we should not be so under the influence of something that it controls us, whatever that something is. The biggest dangers to us are usually not illegitimate things but an over-emphasis on legitimate things. A person can be controlled by materialism, sport, hobbies, gardening, all legitimate things that take up our time. Paul is reminding us of the need of discipline in our use of time.