First of all the belief in a soul and the believe in a mental continuum or the mind as in Buddhism differs in the fact that the soul are eternally of the one same person and when the person passes on the soul continues to live eternally in heaven or hell as the person's soul. The mind as defined by Buddhism is a sort of karmic residue/potential that results in the person deceased reincarnating into a different person if the human realm is the next reincarnation or to the other 5 realms of hell, hungry ghosts, animals, demi god or the gods.
So if we assume, what you refer to soul as the same as the mind, the topic would be logical. Otherwise, mind or soul, we would all be physio-chemical reactions, to quote you, and we will not live again. For convenient's sake I will use the soul jointly with the mind to mean the same thing in the following reply to the topic.
My belief in the soul is based on evidence that many events normally attributed to "luck" or coincident in life cannot be explained satisfactorily. Questions like "why someone is born handicapped while others are born with huge talents?" cannot be answered by attributing to chances, biological factors, environment etc. We can only explain this with some degree of satisfaction if we use the law of cause and effect. The law of cause and effect can be use to explains events within a lifetime where both the cause and effect happens within a single life time. However, most events do not seem to have a cause within the same life, forcing the logic to be extended to a past life or many past lives. If we take this same logic, if there are past lives, therefore there must be future lives. Not just one but possibly infinite future lives as well.
The above argument would negate the body being just of physio-chemical but must have a "soul" that live life after life.
