Personally, I would prefer a duel with guns, arrows or even swords; however, that is not how it is. Instead, it is wrestling, during which the Devil wraps around our minds, grips our bodies, and gets tangled up in our emotions. His purpose? To establish and reinforce strongholds anywhere he can.
A stronghold is a strong hold, a fortress for the Devil inside our thoughts. It is an entrenched thought pattern that keeps us in a way of life outside of God's will, a rut in our mind that we can't seem to get out of. There are a thousand of these plausible sounding arguments, all prompted by the Devil, that keep believers from in the blessings and power of God. Satan paralyzes progress for God's Kingdom with erroneous thoughts, and must prepare for this warfare.