Satan is not God's rival.
That would imply that they're on the same level, they're not. God has no rival, He has no equal.
Satan is not God's counterpart or peer, his influence, power or authority don't even touch the fringe of what our Lord contains.

One is till the CREATOR, and the other is still the CREATED.
The devil is nothing but a copycat, trying so hard to convince you that he's more powerful than he actually is.
He does have limitations/boundaries he can NEVER cross no matter how he tries. For example.

he can't be everywhere at once, only God is omnipresent
he can't read your mind, only God is omniscient
he is merely an illusionist, using canning trickery to manipulate and mislead, only GOD can work flat-out, unmistakable miracles
he's running out of time,Only God is eternal