1 Peter 5:5Likewise, you who are younger, be subject to the elders. Clothe yourselves, all of you, with humility toward one another, for “God opposes the proud but gives grace to the humble.”
If you have had the opportunity to work as group on a project at work, church, or at home, everyone had to submit under the goal in order to finish.  The goal served as almost “a god” to submit to. So if someone tried to venture off and do their own thing, it would disrupt the end goal of completing the project together.
That is how Peter is addressing the elders of the church and everyone else involved. That the goal is for unity, and unity can only come when everyone submits themselves under the goal, God!  Without God being the goal within the church, humility is no longer the common denominator for all of us to do what is best for unity.
In contrast, if pride is the common denominator of our hearts, then what we want to do or not do becomes the main motivator.  Pride always looks to promote itself in and over the group as a whole.  This is why Peter says “clothe yourselves, all of you, with humility”.  Because he knows that our pride will always look to exalt itself within a group, hindering it’s unity…
Whether we are in a family, job, or in church, the moment pride is the means of our motivation, God or unity is not.  What makes us humble ourselves to a common goal such as Christ and unity, is because we desire others to be apart of what God is doing. While pride will always use people to get our own goals accomplished.  Pride alienates, because it must be exalted alone.  Humility reserves that only for Jesus Christ, real love, and unity in Him.
In His Love, Ld