The spiritual significance of a flat earth is inconsequential (it simply doesn't matter....ETERNAL LIFE from the divine/Holy Spirit is our goal, salvation HAPPENED and has been ACCOMPLISHED for all humanity).......SALVATION is PURIFICATION OF THE FLESH ONLY.
In Hebrews 1, we are told that Jesus had made PURIFICATION FOR SIN (the flesh).
Hebrews 9:14 says that purification of the CONSCIENCE can only happen when we learn from the "ETERNAL SPIRIT" to do things right/justly so that our conscience will be clear/pure).
Discussing "FLAT EARTH" is simply/mainly only an EXERCISE in believing new information but will also be useful in explaining to the new generations of worshipers how much we have NOT BEEN TAUGHT (we must escape the lies of the SON OF PERDITION).
SALVATION HAPPENED, it is ETERNAL LIFE that should be our goal.