(Christian standpoint only.)

We know that God and his human creations have a corporeal existence that is a part of their definitions.

We do not necessarily know the nature of this corporeal existence; however, it has been shown to us at various times in history.

For example, at the Transfiguration, we had a glimpse of this permanent, corporeal existence, although it is described inadequately.

So, from an Orthodox Christian standpoint, we know that having a body is a part of your permanent existence, although we cannot say for an absolute certainty what it looks like or even of what it is constituted.