Perhaps like me you’ve always heard the phrase, "there is strength in numbers". I confess this has limited me more than one in endeavoring to take on certain projects where I feared I would not have the numbers. Yet, Jesus, the very Son of God was not intimidated in the least to spend the most important three years of His life hanging out with twelve men, and one of them was an enemy.
There is power in one, if the one you are hooked up with is the ONE:
3 Make every effort to keep the oneness of the Spirit in the bond of peace [each individual working together to make the whole successful]. 4 There is one body [of believers] and one Spirit—just as you were called to one hope when called [to salvation]— 5 one Lord, one faith, one baptism, 6 one God and Father of us all who is [sovereign] over all and [working] through all and [living] in all. Ephesians 4:3-6 (AMP)
The emphasis in this passage begins with an individual making an individual decision to work with others. The individual cannot begin with a premise that promises a certain outcome. Rather, it is each individual making an individual decision that they are going to hold to the premise that in the body of believers that names the Name of Christ that they should operate as :one".The group consensus comes with each individual purposing in their heart that this will be their goal because each individual understands that in Christ there is only "one Spirit", embraced by "one hope’ in salvation. And that salvation consists of "one Lord, one faith, and one baptism".
Our lack of unity in the faith today largely is a result of not understanding that there is "one God and Father of us all" who is at work to bring individuals together in agreement, in unity. Even though God is sovereign, He does not use that power to force or coerce individuals to make that decision. Rather, it starts with "one", who makes a determination that they will receive the power of the Spirit of Christ, which gives them love and wisdom to seek unity among the brethren.
Seem impossible, not according to Romans 5:15 (AMP):
But the free gift [of God] is not like the trespass [because the gift of grace overwhelms the fall of man]. For if many died by one man’s trespass [Adam’s sin], much more [abundantly] did God’s grace and the gift [that comes] by the grace of the one Man, Jesus Christ, overflow to [benefit] the many.
You see that One Man, Jesus Christ gave the power of love to each "one" who will receive it.