Ecclesiastes 4:12 Though one may be overpowered by another, two can withstand him. And a threefold cord is not quickly broken.
When we intertwine multiple cords together we get a rope that is much stronger than the sum of the cords put together; this happens because of the friction between the cords as well as a few other factors.
When we are placed together with other Christians we make a stronger force than just the individual parts joined together because of our differences and our similarities.
God wants diverse people to come together to make a stronger and more able church that can do more to glorify Him than individuals working for themselves.