Being saved while believing in a non-physical resurrection?

[Mark Quayle]

In the Greek, that's "If there is a natural body."

"The body that is sown is perishable, it is raised imperishable; it is sown in dishonor, it is raised in glory, etc. (1 Corinthians 15:42-43)

Two terms are in play here that Paul uses in a specific way rather than common way, one originating with Paul himself: natural body and spiritual body.

Natural body is the perishable, corrupt, weak, sinful (physical) body. (1 Corinthians 15:50)

Spiritual body is a NT term originating with Paul and used by no one else in the NT epistles.
By this term, Paul means the imperishable, incorruptible (immortal), not-characterized-by-sin physical body (1 Corinthians 15:42-44).
He calls it spiritual in contrast to natural, and not in contrast to physical, material, or corporeal.
Paul doesn't use the word "spiritual" to denote the non-physical, non-material, non-corporeal.
He uses it to denote the realm of spirit, usually the Holy Spirit.

So when Paul speaks of a spiritual body, he is not speaking of a non-physical body, but of the imperishable, incorruptible, sinless physical body of the resurrection, in contrast to the natural body
which is perishable, corrupt, weak, sinful.

Exactly.

"So while we are in this tent, we groan under our burdens, because we do not wish to be unclothed but clothed, so that our mortality may be swallowed up by life."
2 Cor 5:4

It is THESE BODIES that will be raised incorruptible. I'm more than 'pretty sure' that what we consider physical in this temporal realm is nothing compared to the real, the spiritual 'physical' to come.