but if I wait long, that you may know how men ought to behave themselves in the house of God, which is the assembly of the living God, the pillar and ground of the truth.
The church of the living God ...  Inherent in this is a comparison with paganism, or rather a contrast, thus: "Church of the living God, not the temple of the dead idols!"  "Pillar and ground of the truth ..."  Paul had seen the marvelous colonnade of pillars which was the principal feature of the great temple of Diana at Ephesus; and something of the meaning of such pillars is inherent in this.  A pillar supports and upholds, exactly what the church does for the truth of God. The word "ground" in this connection has the same meaning.