Purity of the Soul

I was told that the Gemara states, “If man safeguards the purity of his soul by walking in the ways of the Torah, all will be well, but if not God will take his soul from him". Does the Gemara actually say such a statement? And if so, what does it mean?

The statement does appear in the Gemara (Niddah 30b at the end of page). The Talmud is describing the dialog that takes place between the soul and its guardian angel just before the soul makes the transition from the mother's womb to the physical world. The guardian angel is explaining to the soul that it was created in purity and its task is to remain pure after birth.