Ordinarily-Unattainable
Assurance is so rare as to be ordinarily unattainable — the Tridentine position rejected by XVIII.1–4.
This is a contested or rejected alternative.
The Westminster baseline on Assurance is Attainable-But-Not-Essence-Of-Faith. Personas and schools listed below hold this alternative position instead — either because they argued for it at the Assembly (like the Erastians on polity) or because they represent a receiving tradition that departed from the Standards on this point.
Cruxes on this attribute
The Assembly navigated 1 crux that bear directly on Assurance.
Other positions on Assurance
Attainable-But-Not-Essence-Of-Faith WCF
An infallible assurance is attainable in this life but does not belong to the essence of faith; a true believer may wait long and conflict with many difficulties before partaking of it (WCF XVIII.3).
Essence-Of-Faith
Assurance is of the essence of saving faith; every true believer enjoys full assurance — the early-Calvin and Beza tendency softened by the Standards.
Both-Spirit-Witness-And-Marks
Assurance is built upon the divine truth of the promises, the inward evidence of those graces unto which the promises are made, and the testimony of the Spirit of adoption (WCF XVIII.2).