Distinguishing between God and Satan
Assuming Satan exists, how do believers objectively know they are not worshipping Satan rather than God? A similar problem is the possibility that Satan wrote or inspired the Bible by impersonating God, or that he inspired Jesus's actions.
This conundrum examines the basis of religious knowledge. Believers worship an entity called "God" and think he has certain attributes. However, these beliefs could be prompted by Satan and what believers call "God" is in fact Satan. It is possible that a "true God" exists which is ignored by worshippers and has views and attributes quite different from those possessed by the author of the Bible. It is also possible that absolute morality exists and the entity worshipped by believers is absolutely evil. Humans have limited knowledge and experience. We have varying ideas about what constitutes good and bad. As humans, we have no reliable way to distinguish God from Satan.
The Bible states that Jesus was accused of working miracles on behalf of the devil (Luke 11:14-19 , Matthew 12:22-29 ). Jesus responded that their claim is contradictory, "Satan cannot cast out Satan", which is questionable. However, if the devils were agents of the "true God" that were working against the author of the Bible (Satan), it would not be a contradiction for Satan to cast out Satan's enemies.
- "Why should that be omnipotent? Why should that be omniscient? Why should that be perfectly good? It could be a being that is doing it in order to dupe loads of us into having belief in a false religion."
"Never did We send a messenger or a prophet before thee, but, when he framed a desire, Satan threw some (vanity) into his desire [...]"
Muhammad's Satanic verses
Muhammad had an early revelation that said polytheism was true. This was probably motivated by political expediency. He later claimed they the revelation was inspired by Satan and are therefore referred to as the Satanic verses. They were expunged from the Qur'an. 
The Bible says it was written by God
The Bible says it was written by God. However this does not discount the possibility that Satan wrote the Bible and is impersonating God. Relying on the Bible to authenticate the Bible is a circular argument.
Some believers claim they know in their heart what is right and wrong. God can only go good and Satan can only do evil. Therefore they can distinguish between God and Satan and know that God is worthy of worship. However, the our "moral compass" could be the product of either Satan or God. Having in instinctive grasp of morality does not imply our judgement is beyond doubt or not inspired by Satan.
This argument is also undermined by the atrocities that God commanded in the Bible.
The Bible does not lead to Satan
A possible approach is to rely on the description of God and Satan in the Bible is accurate:
- "I am sure you are aware that the result of reading the Bible is NEVER that people worship Satan or believe more in following Satan. "
However, if Satan is the object of worship in the Bible, caused by Satan impersonating God, then the Bible would lead to this result.
A similar objection is to point out that the Bible criticises Satan and predicts Satan's downfall. This misses the point that Satan could be impersonating God and the character "Satan" in the Bible is a red herring (or the "true God").
There must be a foundation for logic
- Logic depends on the Bible being true
- If Satan wrote the Bible, then the Bible is false
- If the Bible is false, then there is no justification of logic (from 1)
- If there is no justification of logic, then one cannot intelligibly argue the possibility of Satan writing the Bible
- Therefore, if Satan wrote the Bible, one could not intelligibly argue that it was possible for Satan to write the Bible
- We are intelligibly arguing about whether Satan wrote the Bible
- Therefore, Satan could not have written the Bible
Point (1) is a false premise: there could exist a source of logic outside the Bible. To claim otherwise is an argument from ignorance. It also falsely claims that logic must have an outside source. Point (2), the Bible might contain a mixture of truth and falsehood (which it in fact does). Point (2) assumes things about Satan that have not been established. The rest is mostly gibberish.
God must have attempted communication
It has been argued that God would have attempted to communicate with humans. This must be in the form of the Bible since no other revelation exists. 
However, there are plenty of other religions in which God might have tried to communicate with humans. Also, God might have tried to communicate outside religious sources. This argument assumes certain attributes of God that have not been justified.
Lack of motive
No one reads the Bible or listens to God anyway, so why bother impersonating him? This argument might be made in jest.
- "Why would he [Satan] bother? I mean, we screw each other over and do the devil's work all the time on our own. Why would he feel compelled to waste his time writing up a manual? "