The conflict between God and the devil has raged since the beginning.  Christians are naturally drawn into this battle by choosing Christ.  But this is a life and death struggle, and those who choose the side of the Lord must fight to win - otherwise, they will lose.  There's no place for slacking off or just going through the motions.

Scriptures:   Revelation 12:1-4;  Revelation 12:5-9;  Revelation 12:10-12;  1 Peter 1:17-21;  1 John 5:4-12;  Luke 14:26-27