Today we pick up in verse 17. In this second section of chapter 4, Paul gives the Ephesians some practical ideas for walking in the Christian life, tangible ways the church can be living out unity and maturity with one another, building each other up. He does this by juxtaposing the old life, which we are to put away, with our new life as believers in Christ. Put Away The Old Life There's a few things Paul uses to identify what our "old self" looked like before we began to walk with Jesus and encourages us to put this old way behind us. According to him, the non-believer has "futility in thinking" (v.17) and is "darkened in understanding" (v.18). This kind of "ignorance" has nothing to do with intelligence, or enlightenment as it would have been called back then (ESV Study Bible, 2269). But combined with their "hardness of heart" (v. 18; in other words, a blindness to God's glory and a lack of knowledge of His love and who H...