What is the cause of the conflict between Satan and God?

Satan wished to glorify himself above all others.... including God. His rebellion against God was the reason that Satan and his followers were cast into Hell.

To set himself in Glory above his Peers,
He trusted to have equal’d the most High,
If he oppos’d; and with ambitious aim
Against the Throne and Monarchy of God
Rais’d impious War in Heav’n and Battel proud
With vain attempt. Him the Almighty Power
Hurld headlong flaming from th’ Ethereal Skie 45
With hideous ruine and combustion down
To bottomless perdition, there to dwell
In Adamantine Chains and penal Fire,
Who durst defie th’ Omnipotent to Arms.