Many people deny spirit, because it's too amorphous a term...

And needs to be understood by the modern fact based mind.

And so it is this- there are a number of subtle bodies interpenetrating the physical one we see.

These bodies all interact.

For example, the thought body effects (and is effected by) the emotional body, which then effects the physical body, through hormonal glands and such.

The bodies we have are not all destroyed by the death of the physical body.

We are said to be able then to operate through a spiritual facsimile of the physical body, but improved and more liberated in action and ability, than the flesh body.