(Only a God who exists is possible to know, so the one we have knowledge about is the true God. Not stories about God, because those cannot be corroborated. Not just stories about people, because that's called history or myth. But stories about people in a living relationship with God, because that is what you will also have if you could believe in Him.
"No-one really knows" is no excuse, because God has made himself known. It would be more accurate to say you don't believe God revealed himself to his creation, which means you ignore anything that claims to be revelation.)
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That's what you believe in, and by all means, it might be true for you... But think for a moment. What if God wasn't who you thought he was. Say, what if god is a woman? Black? What if there's more than one god, or anything and anything is part of god? There are so many possibilities for a higher power that could be translated into the christian god, which may or may not have revealed themselves. If that means i ignore your god, so be it.
And... i choose to ignore the bible because it is a confusing, bigoted, contradicing, and hypocritical piece of work. Everything in there, at least by non-christians, must be taken with a grain of salt
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(A sinner is anybody born under the consequences of sin, whether they believe or not. Since the consequences are universally visible: hatred, immorality, lawlessness, etc. - it is quite easy to recognize yourself as trapped by it. "Sin" is just a collective word for life without God. If someone tells you you live in the earth's atmosphere, it will be true even if you don't believe him.)
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So, you're saying that even though i live the best life i can, try to be kind and equal to everyone... I'm still going to hell? Nice god to believe in, condemning the people who are a little teensy bit skeptical to an eternity of torture. Yeah. Uh-huh. Karma
And umm... You can definately feel the earth's atmosphere. It is there, in front of you.. You can't see it, most of the time, but you can feel it, taste it... hear the wind, smell things carried by it. Definately a very very physical thing to believe in. If someone didn't believe in the atmosphere.. i'd be suprised. Very suprised.
Now.. Something like other galaxies that we only have pictures of and i have no personal experiance? If someone didn't believe in those, it wouldn't be as implausible.