There is much that can be done in the flesh in faux unity. Habitat for Humanity, World Vision, Red Cross, Salvation Army, Food Kitchens, Homeless Shelters, Missions Trips and may other works that while having a grazing hint of spiritual implication, not much of it requires unity. Heck you can do all these things and be a pagan, a wiccan, a Buddhist, a Muslim or an atheist. None of the works of mercy require much unity. You don't even need a church building to do this. The Rotary Club can do all this.
If that is what you desire, then you don't need much in accord with the people you serve with. They can believe whatever they want and you can be tooth and jowl in tandem with them.
On the other hand if you want to do spiritual service (which in theory is why we have church) you have to have unity or it just doesn't work. Teaching, correction, disciple making, prayer, intercession, faith, hope, love, prophecy, spirit and truth worship, deliverance from demons, healing (when it's hard), miracles and communion.
Those things just won't work...well... without unity. Doorpost shaking doesn't happen when unity is lacking. All of the things mentioned above work best, and maybe only, when people are on the same spiritual wavelength. They don't have to be on the same level, but there can't be ecclesial schizophrenia. When the Bible says in James 1:6-8 it is talking about not only a person, it is talking about people, Churches of people, when they come together. If there is wide ranges of opinion, there is going to be doubt and unbelief. When that happens this is the result:
It must be in faith that he asks with no wavering (no hesitating, no doubting). For the one who wavers (hesitates, doubts) is like the billowing surge out at sea that is blown hither and thither and tossed by the wind.7 For truly, let not such a person imagine that he will receive anything [he asks for] from the Lord,8 [For being as he is] a man of two minds (hesitating, dubious, irresolute), [he is] unstable and unreliable and uncertain about everything [he thinks, feels, decides].
30while You extend Your hand to heal, and signs and wonders take place through the name of Your holy servant Jesus." 31And when they had prayed, the place where they had gathered together was shaken, and they were all filled with the Holy Spirit and began to speak the word of God with boldness. Acts 4:30-31