Spiritual warfare is war/conflict waged in the invisible, spiritual realm that manifests itself in the visible and physical realm.
A stronghold is a fleshly way of thinking or living that becomes barriers to the Holy Spirit and thus becomes a portal/door where the enemy can work in or among us to alter our behavior and responses.
The enemy's strategy is to affect culture's way of thinking and value system via demonic influences. The objective of this lesson is to establish biblical principles that wil help you stand firm in the midst of an attack.