We have a reason to contend for our faith. Jude 3-4 tells us that we should contend for the faith we received.
In short, we should defend it vigorously. How? By standing up to the principles of the faith we received from our fathers through scriptures.
Defend, this faith for some has come into corrupt the good word of the Lord.
It is by constant fellowship, involving prayer and the word that we get to defend this faith.
Or how can a man defend that which He does not know? You cannot defend because you have no ground to stand on as you defend.