Explain consciousness (viññāna) to non-Buddhists Problem

In discussions on Buddhist term consciousness (viññāna) with non-Buddhists, it's imperative to start with talking about life in general because---to my understanding---life after all is the physical body we possess with consciousness, i.e., we wouldn't call a physical body without consciousness a life form.

Some non-Buddhists I talked with define life as simply an arbitrary biological phenomena. For example, we humans have sensors, sensor signals are interpreted by a complicated neural network in the brain, decisions and interpretations made as a result are conveyed around the body accordingly, and the motor actions take care of the rest. That's with regard to actions. Thinking is simply a neurological decision process made in the brain. Also, according to them the birth is a result of a sperm and an egg and death 'cos the heart stops.

All fair explanations. But, before even introducing the concept of this continuous consciousness that continues from one life form to another, all is understood biologically. Life is birth + (actions + thinking) + death. All done.

The continuous consciousness that I'm addressing here (that I want to explain to others) is what I have learnt to be what continues whatever the life form we take till Nibbana. 

Question

How would you initiate one to step out of the above box of reasoning and get 'em to think of consciousness? What would be your line of reasoning to counter the above biological reasoning?

Note:
 1. Feel free to change the question if you think its wording is not exact or not understandable.
 2. The counter arguments I requested are purely for the sake of explanation. I've no personal interest in engaging in word-fights!
 3. Consider all sub questions in Question above as one question.
It sounds like you're trying to explain consciousness within a framework that supports rebirth to people who understand consciousness in a (materialistic) framework that won't allow for rebirth. Seeing consciousness as tied to an organism and the development of consciousness in an organism leaves no room for the "migration" of consciousness required for rebirth to work.

Am I correct in understanding this difficulty?

If so, you could try the following...


Get people to abandon materialism.  For many, this is the same as asking them to abandon science.
Explain rebirth in a materialistic framework.  If consciousness is a property of structure, rather than organism then a rebirth mechanism exists by simply having the same structure arise in the future.  Karmic imprints could be explained by neuro-plasticity (which is said to be affected by meditation).  Still, they may ask what happens if this structure is replicated now (and why wouldn't it be, given how much life we have?).  


An alternative is to look at the big picture.  If you are trying to introduce people to Buddhism, why mention rebirth?  The Buddhist path is identical, whether or not one believes in rebirth.  Further, many are attracted to Buddhism (or at least it's secularized variant popular in the west) precisely because of its less supernatural nature.  Introducing rebirth therefore might cause them to abandon Buddhism.  For many, if it's a choice between Buddhism and Science, then Science will win, no contest.