How could that be, two Gods?  

We are led to believe that there is but one God. Well, that's true in one way, but just as sure as the sun rises in the morning, there are in fact two.

Marcion, following in the steps of Paul, declared that it was so, and was branded a heretic, shunned by those who represented the "recognized" Christian authorities.

That possibility was not even considered at Nicea, when the so-called Ncene creed was agreed to and declared.

'Course at that time, it was written in stone that the one God consisted of three parts..the Father, the Son and the Holy Ghost(Spirit).  Not, as it actually is, that God, the Father is uniquely alone, Jesus the Christ is separate as His son, and the Great Comforter, the Holy Spirit an emanation of the Father.  Each is separate and possessed of unique capabilities.

Jesus said that the god of this world is not my god.  Then he turned to  His followers and told them how to pray..Our Father, which art in heaven.  

 First He admits that the world's god is not His, but the Father in heaven is the true God, deserving of their prayers.

In the wilderness, Jesus  was tempted by Satan..the Adversary, who promised him every power on earth.  Who, but the supreme ruler, "god" could promise this?

 There you have it, Satan was and still is the ruler of this world!  

When he was given this power cannot be determined, but I'd hazard a guess that it happened after the destruction of the first Temple..the ONLY edifice that was built as God instructed..the only place of worship that God wanted.  

After this was destroyed by the Babylonians  in the 6th Century BC, which He permitted, there was no other single place for worship..from then on worshipping Him became a personal endeavor..no need for more buildings. 

Jesus taught outdoors.  Paul taught in homes.

Keep in mind though , that even though Satan rules on earth, he is under the guidance of the Father.

Any time you have doubts as to who pulls the strings, return to Job and read again.  

And it has been stated that God is responsible for both good and evil.  He uses His subordinate, Satan, the ruler on earth, to accomplish His purpose, which coincides with His ultimate plan..bobnpaul