Summary: God and the devil are NOT equals battling it out for the souls of men.
I’ve Seen the Light!
The electromagnetic spectrum is made up of radio waves, microwaves, infrared and ultra violet light, x-rays, gamma-rays and visible light. What we see with our eyes is a very small part, less than 10 percent, of the electromagnetic spectrum. There is a whole lot more flying through the air than what we see. If we were to declare that we don’t believe in any of that other stuff because we can’t see it, we would get laughed out of town. We have seen the visible light with our physical eyes, but there is a whole lot more to "see."
The same is true in the spiritual realm. There is a whole lot more flying through the air than what we see. What we see of the spiritual realm with our physical eyes is only a tiny part of the whole spectrum of spiritual reality. There is a whole hierarchy of invisible evil spirits (aka demons) that have been cast out of heaven and now dwell on the earth with us. If we were to declare that we don’t believe in any of that stuff because we can’t see it, we wouldn’t get laughed out of town (or church) unfortunately, because that’s about what everybody believes these days... that there are no devils.
Jesus came to destroy the devil and his works and to set the captives free to know Him personally and intimately. He did that by proclaiming the truth, healing the sick and casting out demons. Everywhere Jesus went He did the same thing. He proclaimed the truth, healed the sick and cast out demons. That’s the way Jesus evangelized.
Not only that, when Jesus sent out the twelve Apostles to spread the gospel, He told them to do the same thing He did:
"He summoned the Twelve and gave them power and authority over all demons and to cure diseases, and he sent them to proclaim the kingdom of God and to heal the sick... Then they set out and went from village to village proclaiming the good news and curing diseases everywhere. (Luke 9:1f)
Next Jesus sent seventy two disciples out on mission and gave them the same marching orders, proclaim the truth, heal the sick and cast out demons. (Lk 10:1f.)
Then finally Jesus spoke to all of us and said: "Go into the whole world and proclaim the good news to all creation... signs like this will accompany those who professed their faith, they will use my name to expell demons... and the sick upon whom they lay their hands will recover." (Mk 16:15f)
Jesus never changed his mission statement and the methods he wanted his disciples to use to proclaim the Kingdom of God. He never separated evangelism from healing and deliverance. We did. The only change He left us was: "Amen, amen, I say to you, whoever believes in me will do the works that I do, and will do greater ones than these, because I am going to the Father." (John 14:12). When Jesus says "Amen, amen", that means listen up, this is very important for you to know. Not only does Jesus want us to do the same works He did, but even greater! We are not free to change the mission statement Jesus gave to us.
The bible says that "the kingdom of God is not a matter of talk but of power." (1Cor 4:20). All we do nowadays is talk about the gospel. We have no power! St. Paul would say to us, you senseless Americans, who has cast a spell over you (Gal 3:1). We proclaim the truth, but we don’t heal the sick and cast out demons. We are operating at 33 % efficiency and wonder why our evangelization programs are so ineffective.