Is it the 5 Solas, or the 5 points of the fundamentals of the faith declared back in the 1910's. Are there essentials that are underneath non-essentials to the above?

Why I'm thinking of this is that a forum friend on another board is encouraging his denomination, EFCA, to remove its standard regarding pre-millennial only. He thinks the denomination standard should include a-mil and post-mil. (I gather his denom lumps historical pre-mill and dispy pre-mill together). IOW, one's view on eschatology is really non-essential. I do think the 3 views except for dispy pre-mill are within orthodoxy, but is that where the essential vs non-essential argument flows? In my denomination there is a growing (still distinct minority) traction in regards to women deaconesses. The denom's standard on this seems essential when it comes to church polity, but non-essential when it comes to soteriology.

How best to view this essential vs non-essential elements.