Why does one religion have to be right?

I'm so sick and tired of hearing that Christianity is the only way, that Muslims are all killers, and that their bibles call them to kill at will and as a God fearing person, who chooses to not identify to any one religion, can I just say...yall (religion extremist) are a bunch of crazy crack heads!! 
Who says Bud ah wasn't God in some form that some unknowing human being gave him.?? Who says Allah isn't God?? Who says God's true name is even God??? 
God is just a English word for higher power...as is Allah...it's actually a word for God, but still...bud ah called its followers to be peaceful...kind and caring..God called its people to love unconditionally, Allah called its people to defend themselves and fear God(Allah)...how is this wrong?! How is any of these beliefs wrong?? 
You're telling me that because the Christian incomplete bible doesn't say to defend yourself against those that would harm you, you should just let others harm you...right.... cuz that's gonna go over like a ton of bricks in this day and age....
You're telling me that because there are those that have twisted the Quran to shape their own evil thoughts and actions that all Islamic believers are killers?? With that thought...wouldn't all Christians be hypocrits?? Because Christians go to church on Sunday, and Wednesday, and then every other day of the week live like sinners...
I read this book growing up about 5 missionaries who went to a remote land and tried to bring tribesmen to God, and we're murdered before they could learn anything about God...years later these men's wives went back hoping to bring the word of God to them...but in the time that there was no one to witness, God had shown himself to them, through the trees, the wind, and the sky, through his creation alone they learned of a higher power...and gave it a name...
What if God could show himself to humans in different ways and be given different names? What if everything we humans have ever known about the higher power out there is completely wrong?? The Christian bible says that no human being can ever fathom God, what he is, who he is, or what he/she for that matter is capable of....what more must we know and believe than just to love your neighbor, defend yourself, and be a peaceful race?? 
Religion is practiced, relationships are built...rant over