Some people believe that God and Satan are equals. They might worship God in preference to Satan, because God represents good. On the other hand they might not blame Satan for his evil, believing that without Satan’s evil, God’s goodness couldn’t be known.
Some believe that if the father of evil did not exist, then the Father of righteousness could not exist either. In the spiritual and moral realm, so the theory goes, you need to have the darkness in order to have the light.
For example there is the Chinese philosophy of yin and yang. Even divinity is regarded in this way: there cannot be a good God without his evil counterpart.
This view not only makes God and Satan equal, but to some minds makes them one entity. Many religions hold that every reality has two essential sides, good and evil. Incidentally, some religions, or schools of thought within religions, do not believe in real beings such as God and Satan, but view these "gods" as merely imaginative personifications of the principles of good and evil.
The tension between good and evil is resolved differently in different religions. Some attempt to subjugate evil to good (or vice versa), others to balance the two, and yet others to eliminate the consciousness of both.
Now let’s consider three arguments from the Bible against Satan being equal to God.
Christians believe that God is "the blessed and only Sovereign, the King of kings and Lord of lords, who alone possesses immortality and dwells in unapproachable light, whom no man can see. To him be honour and eternal dominion, Amen" (1Timothy 6:15-16).
Satan and his angels are the enemies of God and we struggle "against the powers [of evil], against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly realms." (Ephesians 6:11-12).
God does not need this darkness. He is independent of it. He has no fellowship with it. There is no nexus between God's righteousness and Satan’s evil. "God is light and in him is no darkness at all" (1John 1:5).
If the darkness ceased to exist, God's light would still shine. It will do so in heaven. "There will no longer be any night... the Lord God will illumine them" (Revelation 22:5).
God’s light "shines in the darkness" (John 1:5). God's light overpowers Satan’s darkness. When Satan’s darkness is banished, the divine Light will not be diminished.
God’s light is not like starlight. You need the night sky to see the stars shine. Rather, God’s light is like the sunlight. The sun, that bright and morning star, banishes the darkness from the sky and shines without any need of night.
Any idea that God and Satan are equal opposites is shattered by one great fact in Christian belief, namely that God has always existed. God was "before all things and by him all things came into being" (Colossians 1:16-17, John 1:1-3).
In the New Testament, God is considered to be "the King eternal, immortal, invisible, the only God" (1Timothy 1:17). Satan, by contrast, is merely a rebellious creature of God who had a beginning. He is not like his Creator who is God "from everlasting to everlasting" (Psalms 90:2).
Satan is not an eternal god; he is therefore a lesser being than the King Eternal.
Incidentally, you will have noticed that in the above quotes there is reference to Jesus Christ. The New Testament recognizes three as one God. Christ is proclaimed as God (John 1:1, Hebrews 1:8).
The Holy Spirit is also God —eternal (Hebrews 9:14), all-knowing (1Corinthians 2:11), everywhere present (Psalms 139:7-8).
The Bible’s doctrine of the divinity and equality of the Father, the Son, and the Holy Spirit, demonstrates that the New Testament sees no equality between God and Satan. Satan is only one, not three —and one who is only one does not equal three who are one, any more than one line equals one triangle.
It boils down to this: Satan is without divine nature —it is nowhere attributed to him in the Bible. So he is, most obviously, a lesser being by far.
Revelation pictures Satan in a parody, as three Beasts: the Dragon, the Beast, and the False Prophet. But these are unable to show equality with the three who are God. In the end, the three evil beasts are thrown into the lake of fire (Revelation 20:10).