How do you know ? Why should non-believers believe that ? Because it's written in the Bible ? But, then, if we are to trust the Bible, what should we believe when the Bible apparently contradicts itself, which happens regularly from the beginning to the end of the text ? For instance, the book of Genesis 1.20 to 1.26 tells that God created the animals on the 5th (birds & fish) and 6th days (for the rest) and that he created Adam AFTER that (Genesis 1.27). Why then, Genesis 2.18 and 2.19, suddenly states the contrary, e.g, that man was created first, and that animals were created after, in order to serve him ?
Really, I do not mean to offend you. I simply would like to point out that when you claim that "reincarnation is a demonic lie" because the "son of god" told it, the argument will never convince a non believer, since, by definition, a non believer does not share the very belief that gives credence to the argument you rely on (an "authority argument"). At the time of Jesus, there were many preachers who claimed to be "the Messiah". And even to this day, self-proclaimed Messiahs appear here and there. So why should a random fellow trust one instead of the other ? Because of his extraordinary feats ? They all claim extraordinary feats ...
Anybody can tell other people : "You are all wrong. I have the truth. If you believe differently, this is simply because you are deluded idiots", but I doubt this will convince them ... which is a pity if indeed they were wrong !
That's why, if you believe in something, and if you think it is The Ultimate Truth, it is better to start your sentences by "I believe that ...". It will be less offensive to others and might even help you to convince some of them in the long run. And then, of course, relying on rational arguments instead of using circular arguments to strenghten your case would also help.
Now, my personal belief is that we are like tiny dragonflies flying over a small pond, ignorant of the vastness of the ocean. Our knowledge is very limited, and we are forever unable to fathom the true nature of the world that extends far beyond. Whatever we see, hear and smell, we interpret through our little brains. What some will see in shining red, will appear green to others. Whatever we think is conditioned by our former experiences. If nobody had told me of the Bible, I would never suspect its existence. Therefore, we know nothing. Believing that we know something when we know not : that is the worst possible "demonic lie".
If there is an afterlife "judgement", I cannot believe a fair "god" could punish anybody for knowing his own limitations and refusing to abide blindly to any given faith, just because he was told to do so by a son or prophet he never had the opportunity to meet or discuss with.