Why does James 5:16 command us to "confess our sins to one another"?

To understand it correctly, James 5:16 should be seen in its context – as a part of the passage from James 5:13-18. When we do so, it becomes apparent that there are two processes mentioned in these verses – physical healing and trespasses or sins. While the healing being mentioned in James 5:16 is a continuation of the thought of healing given in 5:14-15a; the confession of trespasses or sins mentioned in James 5:16 is not for their forgiveness – since, that has already been stated as accomplished in 5:15, prior to asking the confessing to one another in 5:16. The word used here in the original Greek language and translated as ‘confess’ into English, is ‘exomologeo (ex-o-mo-lo-ǰe'-ō)’, and means to acknowledge or (by implication, of assent) agree fully, (Strong’s Bible Dictionary).

To help us understand it better, we need to keep in mind two other verses related to this thought. These two verses are, first, 1 John 1:8-10, where the apostle John, by using ‘we’, and the present tense ‘have’ (instead of the past tense ‘had’) is saying that everyone – he included, sins, even now; and second,Galatians 6:1-2, where the Apostle Paul is exhorting other Christian Believers to lift up and help in the restoration of those Christian Believers who somehow have fallen into some ‘trespass’ or ‘fault’, i.e. have done something wrong; and those helping should also bear in mind that at some time they too can fall into a similar predicament. These references help us understand and accept the fact that Biblically speaking, even established and mature Christian Believers have a tendency to fall into sin, to commit errors or trespasses, to fall short of expectations or standards of morality expected of them. In other words, nobody is perfect and above reproach, everybody always needs God’s grace, strength and forgiveness to remain honest and true to the Lord, and may at times need to be extricated out of unpleasant situations by the Lord.

With the above in mind, coming back now to James 5:16, we can surmise that what is being implied in the verse is that “do not be overly righteous, nor be a hypocrite; do not have a ‘holier-than-thou’ attitude, considering yourself over and above everyone else, or others around you. Rather, be humble and have an attitude of accepting and acknowledging that you too can falter and commit sin, therefore ‘confess your trespass to one another’ i.e. maintain an attitude of accepting and acknowledging before others that you too are prone to errors or sin, just as the others are, and you too need the prayers and help of others for your restoration, whenever you fail or fall.”

This verse is not saying that we need to go and declare our sins and short-comings to people around us, and our doing so will contribute to the forgiveness of those sins. Rather, it means to say that instead of being haughty, we need to remain humble and open to any correction from others; as and when they see some short-coming in us. Whenever our fault or trespass is brought to our notice, we should be gracious and humble enough to accept (‘confess’) it. We should also seek the prayer support of other Believers to keep us that way, or to be delivered from the situation, since the prayers of God’s people are a very effective means of help in any need.