1 Corinthians 11 19

'For there must also be factions (hereses) among you' refers to heretical groups in the midst as the Greek word 'hairesis' is used. There must be a counterfeit in order that the true thing may be recognized!

Paul is saying that the true leaders and those deserving of recognition in the church will be seen because of the exposure those who are heretical in their midst. The word 'recognized' literally means 'shining forth'. Those of true character and ministry will shine forth when compared against the dark heresies in the church.