Writing from prison in Rome some 10 years after he helped found the church in Philippi, Paul still felt such a bond with those believers that he insisted they "partake" with him in his "defence and confirmation" of the gospel ministry.
The key words here are "defense" (Greek apologia) and "confirmation" (Greek bebaiosis). Both words are not common in the New Testament text. Together, they describe a mission attitude that should anchor our approach to ministry.
Apologia, in its various forms, is most often translated "answer." Peter used this term in a passage that urged Christians to be "ready always to give an answer |as in, an answer that is logically sufficient| to every man that asketh you a reason of the hope that is in you" (1 Peter 3:15). Paul used apologia twice to the Philippian church; both times stressed the "defence of the gospel" (Philippians 1:17).
Bebaiosis and its associated terms convey the meaning of firmness, or having been established. Paul encouraged the Colossian church to be "rooted and built up in |Christ|, and stablished in the faith" (Colossians 2:7). Peter tells us to "make |our| calling and election sure |same word, bebaiosis|" (2 Peter 1:10).
Thus, our witness and declaration of "the power of God unto salvation" (Romans 1:16) must be "with logic" (apologia) to defend the precious Truth, and with an eye to "establish" (bebaiosis) that Truth in the mind and heart of those newly converted. The gospel tells who Christ is (the Creator, the incarnate Word, and coming King) as well as what He did on Calvary. HMM III http://www.icr.org/article/5941/