Yes, there is a battle waging , but the battle has been won. We can expect oppostion, but never defeat. Jesus was victorious. Too many christians give satan too much weight and forget completly the sovereignity of God. We are told again and again , not to fear! There is no secret here. God has His plan and He will succeed. So there is no place for a defeatist mentality. Satan’s cause is a lost cause. Once you are a believer you automatically recieve the Holy Spirit and have as Peter says, ‘all you need pretaining to life and godliness.