In a building with pillars, each pillar bears a load, but not all pillars bear the same load because some support a load bearing wall, while others help support the load of others.
For UNITED Church to be strong and productive this same concept must be in place because each member has something they can do for the cause of GOD. Some will bear more of burden and some less, but the whole point is that when the church works together in unity using their various talents, great things can be accomplished.
Paul illustrates the idea in 1 Corinthians 12:13:
For by one Spirit we were all baptized into one body -- whether Jews or Greeks, whether slaves or free -- and have all been made to drink into one Spirit. 14 For in fact the body is not one member but many.
20 But now indeed there are many members, yet one body. 21 And the eye cannot say to the hand, "I have no need of you"; nor again the head to the feet, "I have no need of you." 22 No, much rather, those members of the body which seem to be weaker are necessary. 23 And those members of the body which we think to be less honorable, on these we bestow greater honor; and our unpresentable parts have greater modesty, 24 but our presentable parts have no need. But God composed the body, having given greater honor to that part which lacks it, 25 that there should be no schism in the body, but that the members should have the same care for one another. 26 And if one member suffers, all the members suffer with it; or if one member is honored, all the members rejoice with it.