1 John 2:13-14:
I write unto you, fathers, because ye have known him that is from the beginning. I write unto you, young men, because ye have overcome the wicked one. I write unto you, little children, because ye have known the Father.
I have written to you, fathers, because ye have known him that is from the beginning. I have written to you, young men, because ye are strong, and the word of God abideth in you, and ye have overcome the wicked one.
See also:
Who You Are and What You Have
You Have the Victory, Not the Advantage
Sickness Is the Power of the Devil
How to Deal with the Devil
Notes on Luke 10:17-20