The words "redeem" and "redeeming" occur in at least 59 places in the King James Bible, with the overwhelming majority of uses found in the Old Testament. Additionally, in the KJV, the English word "time" appears in at least 563 verses. Interestingly, the apostle Paul uses the phrase in question at least twice in Scripture.
In the book of Ephesians Paul states the following.
So then, take heed that you walk circumspectly, not as fools, but as those who are wise, redeeming the time, because the days are evil. For this reason, do not be foolish, but understanding what the will of the Lord is (Ephesians 5:15 - 17, HBFV).
Bible translations such as the Holman Christian Standard and the New American Standard do not use the word redeem in the first part of Ephesians 5:16. They translate the phrase as "making the most of your (the) time." Other versions of Scripture, such as the New International Version and the New Living Translation, use the phrase "making the most of every opportunity."
The Greek word exagorazo (Strong's Concordance #G1805), translated as "redeeming" in Ephesians and Colossians, means to rescue something from loss or redeem it. It can also mean to pay a price to recover (reclaim) something from another (Thayer's Greek Definitions).
For example, let us say you want to borrow money from a bank and have to offer some land as collateral (meaning if you do not repay the bank loan, they can take legal possession of the property). When you repay the loan, you remove any claim the lender has over the land and redeem the property.
The Complete Word Study Dictionary defines exagorazo as ". . . by prudent and blameless conduct, gaining as much time and opportunity as possible in view of persecution and death. The word generally means to buy up, to buy all that is anywhere to be bought, and not to allow the suitable moment to pass by unheeded but to make it one's own."
One of the most well-known Biblical references to Jesus is as our Redeemer or One who can redeem us (Job 19:25, Isaiah 41:14, 59:20, etc.). He is called this because his perfect sacrifice pays the debt we humans owe because of our sins. The Bible states that those who have repented and become true Christians are "bought with a price" (1Corinthians 6:20, 7:23, 2Peter 2:1).
Paul admonishes us to redeem the time in our lives because "the days are evil," meaning that humans in general are under the rule and deceptions of Satan the devil (John 12:31, Ephesians 2:2, 6:12). He admonishes Christians to not idly sit by and let the darkness of this world dictate events but rather to make a conscious choice to do good works and let the light of God shine through them (Matthew 5:14 - 16). Even if evil personally comes upon us, we are commanded to not respond in kind but instead overcome it by doing what is right (Romans 12:20 - 21).
Real life examples
What are some concrete examples of how Christians can redeem the time, as God wants us to do? Some of the many things believers can do are as follows. We can do our Father's will (Ephesians 5:17). We can encourage other people in their Christian walk and selflessly serve them (Ephesians 5:18, 21, Galatians 6:10). We can meet with fellow believers in order to worship and praise the Eternal together (Ephesians 5:18). We can regularly thank God, through Christ, for his blessings and calling (verse 20).
Additionally, we can redeem the time but not repaying evil for evil but rather doing as much good as we can (Romans 12:20 - 21). We can help others, especially those who are called, to bear the difficulties and trials that come upon them each day (Galatians 6:2). We can also pray for others, especially those who are spreading the gospel (Colossians 4:2 - 3).
By being zealous to redeem our time on earth, meaning we dedicate our lives to doing as much good as possible, we not only bless others but lay up for ourselves eternal treasures (Matthew 6:19 - 21).