Jude 1:3
3 Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints.

Ephesians 6:10
10 Finally, my brethren, be strong in the Lord, and in the power of his might.
11 Put on the whole armour of God, that ye may be able to stand against the wiles of the devil.