In 1 Corinthians 12, Paul spoke against those who would spread doctrines of "little brides" and "chosen few" from the Christians that make up the body of Christ.
Paul said just as our own bodies are one, yet have many members, so is the Body of Christ. All members of the body, though many, are still one body! With the same Holy Spirit, we were all baptized into one Body. The Holy Spirit that was freely given to us by faith brought us together -- Jews or Greeks, slaves or free, everyone! We were all made to drink of one Spirit!
Paul said that those who would separate themselves from other Christians were silly. What if your own foot decided that since it were not a hand, it did not belong to your own body? Because it is a foot, does that make it any less part of your body? If the whole body were a foot, how would you even function!
The eye cannot say to the hand that it no longer has any need of it. Nor the head to the feet. All parts of your body, even those that seem to be weaker or less honorable are still part of your body! Paul said that we actually bestow greater honor on the parts of our body that are less desirable, because we cover them up!
Our own bodies are like the Body of Christ. God composed our bodies, giving greater honor to the parts that lacked honor. So there is no division in our own bodies, all members care for the other members of our bodies. If one member of our bodies suffer, all members suffer together. If one member is honored, all rejoice together.
Christ is the foundation that binds His body together.
As Christians, we should ask ourselves: Which foundation did we choose for the body we became a member of? Is it the foundation of Christ, fellowshipping with all other Christians weak or strong? Or is it the foundation of a man, separating from other Christians like the foot from the hand? Were we taught that such a small little 'elect' group would be the 'little bride,' or were we taught the same message Paul taught? Do we decide we do not like a certain group of Christians, like our heads to our undesirable body members? Or do we lift them up with love and kindness, covering up their weakness with our faith?