If Satan, God, Jesus and the Jewish and Muslim Gods all talked it out, what would happen?

Ummm...

Well, to answer effectively, we need to establish some "ground rules". First, theologically speaking, Judaism, Christianity, and Islam share a belief in a common God (I know, I know...some folks are going to disagree here, but hang with me). Judaism is the oldest of the three, and the progenitor of the idea of the coming Messiah...whom Christians define as Christ. Christianity accepts the legitimacy of the entire Hebrew religious legacy, diverging in that Christians believe with His death and resurrection...Christ paid the eternal price of blood sacrifice for sin, offering salvation and freedom from (or fulfillment of) the "law" (albeit without removing the mandate to live in the spirit of obedience to the law). Islam also (very generally) accepts the legacy of the Old Testament...though they (again, in a VERY simplified sense) diverge from either Judaism or Christianity regarding not only the nature of the law, but the impact of their "prophet" and his teachings on "true" faith; some would say "adding" an additional layer of theology that isn't strictly compatible with either of the former. As such, it may be VERY, VERY generally stated that all three share common beliefs...but differ greatly on what they believe the ultimate meaning of those beliefs relates to mankind. We also have to accept that within each of these three, there are various sects, denominations, and even individual "interpretations" which can and often do diverge RADICALLY from the doctrinal teachings of the same.

Satan...is generally regarded by all three as the enemy, albeit under varying names, allegories, or connotations.

So-I don't think the various "gods" of these faiths could have a conversation...they are all one in the same. However, it is logical to presume that if that's the case, only one could be the "true" faith in obedience to the one God. Which comes down to whether or not one believes the Messiah is yet to come...has come already...or was misunderstood altogether. I believe if a Jew could be convinced Christ was in fact the Messiah...a Christian could be convinced that Salvation doesn't dismiss the obligation to respect the "law"...and a Muslim could be convinced that their teachings are either misunderstood, misapplied, or false altogether...you could see hegemony between the three.

Trouble is... Satan is always making the counter arguments, and inspiring humanity to tear itself apart, as opposed to come together under God.

I believe that satan was once an angel of God. He thought that he should be superior to God and was caste out of heaven. Jesus is a part of the trilogy as God the father, God the son. and God the holy spirit. The christian bible, The Koran, and the Jewish book are the same in the old testament. Allah is another word for God. The Jews are Gods chosen children. All except the Jews have a spiritual leader. The Jews are awaiting the arrival of theirs. Mohamed for Islam, Buddha for Buddhism, Confucius for Confucianism, Jesus for Christianity (The only living God) Etc. All of them get along fine with each other except the Muslims. What they would say to one another would probably be how to handle the bad boy amongst them.