Are all the religions really only worshipping ONE God just with different names?
No, not one god. The demands of each religion are different, as is the character of their god. For instance, the God of Israel. the Father of Jesus Christ, does not demand human sacrifice as in some other religions. Nor do the followers of Jesus Christ have any command on them to wage war, which is different to Islam. Make a list of those qualities we perceive as good. We see them as good, because they define the character of God. Now find which god matches those characteristics. Congratulations, you have found Him.
Some could be seen as that like Jehovah and Allah but others not so like Buddha is not a God per say and is not seen as from above but a guide and was a human being. There are others as well that are seen as God but with a different name. I believe in God the christian God that sent his son to die for us.