Dear Mark:

Spiritual warfare is the battle waged by Satan and the fallen angels against God and His angels and children.

St. Paul described this in Ephesians 6:10-12 

Finally, be strong in the Lord and in the strength of his might.  Put on the whole armor of God, that you may be able to stand against the wiles of the devil. For we are not contending against flesh and blood, but against the principalities, against the powers, against the world rulers of this present darkness, against the spiritual hosts of wickedness in the heavenly places.

Our first Pope, Pope St. Peter warns us in 1 Peter 5:8

Be sober, be watchful. Your adversary the devil prowls around like a roaring lion, seeking some one to devour.

Spiritual warfare can be found in our own lives in the form of harassment from demons (including obsession, oppression and possession). It is also found in our culture and in our nation as demons attempt to influence us through influencing politicians, cultural leaders and role models, cultural icons, musicians and singers, artists, writers, T.V., movies, education at all levels, the New Age and the occult. This is all to influence us away from virtue and from God. 

God Bless,
Bro. Ignatius Mary