Nehemiah 4:2 is a spiritual testimony against OSAS as people are "stones" in the spiritual sense--1 Peter 2:5--and they must be revived from the heaps of rubbish--the chaff that is burned with unquenchable fire--because they are burned--they have been cast into the lake of fire and will be revived once they have suffered in accord with their sins.

OSAS isn't Scriptural, and even Revelation speaks of overcomers being warned by Jesus to stay away from the sins that will get you cast into the lake of fire. Revelation 21:7-8.

Believers are said to never perish because for the vast majority of believers that is true. But there is an exception to every rule in the Bible. The Lord hasn't shown me where in the OT that that rule is revealed, but it holds true. And just as everyone who professes with the mouth and believes with the heart will be saved, so also will all those who commit the sins of Revelation 21:8 be cast into the lake of fire (although there is even grace here as well, as it says in Job 33:29.