1 Corinthians 11:18-19 KJV
For first of all, when ye come together in the church, I hear that there be divisions among you; and I partly believe it.
For there must be also heresies among you, that they which are approved may be made manifest among you.
The Word of God sets out two sorts of people who will be "among you" that is, within the church.
The first are "heresies"
The word means "choice or disunion." There are those whose choices in the their personal and spiritual lives create disunion in the church. They, because of their choices, never become fully followers of Jesus Christ. They might be believers but their choices make them to be separated from those Christians whose desire of to grow in the grace and knowledge of the Lord Jesus Christ. The heresies may not be such as to be evidence of false profession in Christ - although that is certainly possible, but they are such as to create division in the local church.
The second are "approved."
This word means "tried and accepted." This group in the church rise to the top as Christian servants and leaders in the work of the Lord. They have been through the fires of trial and continue to grow for the Lord. They are faithful and can be counted upon in the ministries of the church. Their testimonies stand true to God even though they suffer difficulties.
The heresies that arise serve as a backdrop to illuminate and contrast those whose choices prove to be constantly for God.
I am reminded of the parable of the wheat and the tares. They both grow up together. They are both in the same field. For some time it is difficult to tell them apart. But there comes a time when those that are approved become manifest and apparent. It is obvious. We will never remove all heresy and division and people who make poor spiritual choices from our church. But we will always look for those who stand out as tried and approved before the Lord because of their very clear godly choices.