1 Corinthians 3:5 (ESV)

5 What then is Apollos? What is Paul? Servants through whom you believed, as the Lord assigned to each.

After pointing out the Corinthians’ wrong approach to human leaders, Paul goes on to explain the right approach. The foundational truth about the church’s leaders is that they are servants. They are instruments in God’s hand, whereby he brings his elect to faith.  

The phrase as the Lord assigned to each can be understood in two ways. The word each may refer to Paul and Apollos, who have each been given the task to lead certain people to faith. It may also refer to the believers in Corinth, who have each received their faith from the Lord.