Good vs. Pure

A good conscience vs. a pure conscience

1 Timothy 3:9 says, “Holding the mystery of the faith in a pure conscience,”

2 Timothy 1:3 says, “I thank God, whom I serve from my forefathers in a pure conscience.”

For the exercise of our spirit, we need not only a good conscience but also a pure conscience.
When a brother cares more for the gospel work than for the Lord, the gospel is a substitute for the Lord in this brother’s life and work. It is something for the Lord, but it is not the Lord Himself. .... He has a good conscience, but he does not have a pure conscience.
(The above is taken from "The exercise of our spirit", Chapter 1. To read its entirety, visit http://ministrybooks.org/.)
Those with a pure conscience are taking Christ as their center and focus. Hence, their life and work build up the Body of Christ. Those with a good conscience may have the appearance of serving the Lord, but the Lord may not approve them (Matthew 7:23).