Chief, i agree, only God knows everone's heart. Though i do not agree in heaven or hell as an eternal resting place. I believe in reincarnation - the body dies, it is shed like a coat and the mind/spirit (different from the brain) maybe i will use the term consciousness - fades a bit and then is reawakened with a new incarnation. (much in the way that this happens every night when we go to sleep). In my beleif though people do not revert to animals, rather each person has a chance each lifetime for greater conscious awareness, the unfolding of ones spirit into something greater.
But i agree, God or the Universal Mind from which all life springs, does know our hearts and is always for us, not against us, always producing experiences and situations or circumstances designed to teach us and carry us further along in our spiritual dvelopment.
To me SIN is missing the mark, misunderstanding or making a mistake, taking a wrong turn in life. Thus God would not hold sin against us as a form of eternal punishment but continually try to get us back onto a better road, one that will help us to grow - not cause us to wither in despair.
Still, people need to be held accountable for their actions and to me the universe has a wonderful system for that, KARMA, simply action and reaction, as you sow so shall you reap.