God is our final say in who and what's negative and who and what's positive in our lives. It is best not to have this so over-simplified as the illusioned superstitionists have it; an infinite being's tests may not always be so flowery, and the things we may see as positive are in many cases simply desires of our sinful nature. We are to protect our spirit without falling into the narcissistic mistake of trying to protect our selfish emotions, which the latter, in turn, is more than unlikely to bring peace and happiness. But rather guilt and emptiness. When one walks around constantly, in his mind, attempting to separate positive versus negative people, he is already controlled by something even worse than those he calls the 'negative people', and that is before he spots it soon enough to avoid it as he hypocritically tries to avoid them.