I say the truth in Christ. — The meaning of this expression seems to be, “From the bottom of my soul, in the most sacred part of my being, as a Christian man united to Christ, I make this solemn asseveration.”
My conscience. — Here, as in Romans 2:15, very much in the modern sense of the word, the introspective faculty which sits in judgment upon actions, and assigns to them their moral qualities of praise or blame. “This conscience of mine being also overshadowed with the Holy Spirit, and therefore incapable of falsehood or self-deception.”