He was referring to the wicked spirits, especially religious spirits , that at times motivate us to become defenders of truth. They disguise themselves. North in the scripture stands for evil and wickedness. It's those religious wicked spirits at work. There's a scriptural principle here.
People respond when truth is proclaimed in love.
We're required to hold to it lightly and to be willing to give it away, not to own it. We don't have to protect truth or try our best to preserve it. Truth doesn't belong to us anyway. It belongs to Him. That's not what it means to contend for the faith.