This theme is throughout the Bible. It starts way before this passage in Isaiah and continues through the New Testament. Paul repeats it in 1 Corinthians 4:7. Jesus, quoted by Luke in Luke 17:9 – 10 echoes the theme. If we accomplish anything for the Kingdom, we are just doing what we are supposed to be doing and doing it with the gifts and abilities we have been given and through the strength of the Spirit.
Why would we promote ourselves? It is Christ whom we should be promoting, is it not?