As Peter, James and John were so-called pillars of the early church (Gal. 2:9), so was Timothy to be in Paul’s stead in Ephesus.
Paul couldn’t hop a plane to Ephesus. Ergo the following instructions were vital to the life of the church there:
14I am writing these things to you, hoping to come to you before long;15but in case I am delayed, I write so that you will know how one ought to conduct himself in the household of God, which is the church of the living God, the pillar and support of the truth. 1 Timothy 3:14
Guarding the truth in the local assembly is a full-time job. It is the most important job. With it comes, by necessity, an insistence that Christians live by a certain code of conduct, for unrighteous living erodes the church’s foundation (truth). Righteous conduct among church members provides powerful structural support to the message of Christ. If absent, we are on shaking footing.
Another word picture in this passage is of a “living” breathing organism. We all know that any foreign cell in the blood, i.e. cancer, can seriously impede the body’s function, and ultimately, if it multiplies, can cause death. There fore, it must be eradicated. This is the job of the church leader, and it is primarily done through authoritative sound biblical teaching.