Even if you gash through a galvanized surface, the exposed metal below won’t rust. That’s because the adhering zinc that constitutes galvanization blocks the electric activity in steel that is part of the oxidation process. So it can’t oxidize, and thus no rust.
Paul described faith as a shield, which invoke images a heavy metal disk held aloft to block arrows, spears or sword blows. With modern metaphors, we could enhance our understanding of faith. Maybe it’s more like galvanization. Even if it’s not covering perfectly, it prevents corrosion.
Prayer, Bible study and fellowship are like galvanizing your spiritual interior.