From Genesis to Revelations, God uses the Scriptures to speak to His own people. Christ Jesus is revealed throughout the entire Bible. The Bible teaches us about who Christ Jesus in His entirety. God the Father, Son and Holy Spirit never change. His Word is rock solid and leaves no room for change.
The spiritual battle was going on before mankind began on earth. God created all human souls. The devil made an attack on mankind knowing it would hurt God. Long after mankind is no longer in this world, the battle will continue. 1Cor 15:26, The last enemy that shall be destroyed is death.