This is very true, however there are also some very fundamental differences.
Christianity: Belief in the old and new testaments of the bible, belief in jesus as the only way to heaven.
Judaism: Belief in old testament of the bible, belief that any one of us could be the messiah.
Islam: Belief in the Koran, belief in muhammed as the prophet. Belief that blowing yourself up and killing infidels awards you with 49 virgins in heaven.
Buddism: This one sort of deviates. Siddhartha describes the journey of buddha as he begins his life in a place where he knows no evil or pain (kind of like the garden of eden). When he leaves his walls he finds suffering and contemplates it until he gains enlightment and is no longer of this Earth.
The words you speak of all these religions being similar and being maybe combined is what is called the Ecunumical movement, it is semi endorsed by the catholic church and is an effort to have all the world under one religion to prevent fighting. According to the bible this would be disastrous as no religion including christianity can join another religion and keep it's most basic precepts, therefore corrupting all religions.
"Mac, you ever been in love?" - "No, I've been a bartender all my life."