Is it true that a bad apple will spoil the entire congregation? NO! There are hundreds of Christian religions today. They don't disfellowship Christians. Why? Because they are followers of Christ, and Jesus did not teach a strict set of rules and regulations. All he taught was for us to be an example of God's divine love.
There's plenty of room for debate in every Christian church. The 'law of Christ' is freedom. Jesus said his followers would be recognized by their love. Jesus loved his neighbors, enemies, and even his executioners. The 'law of the Christ' is the law of unconditional love for everyone, no matter what they believe in. The unifying force in a true Christian religion is unconditional love, not unity of beliefs!