Many true believers lack full certainty before death because they look too much at their unworthiness
Sincere believers may lack full certainty even until death.
The cause is fixation on personal unworthiness, not distrust of God’s promises.
Latin
XVIII. Itaque non pauci sunt syncera fide in Christum praediti, & per consequens vere Deo reconciliati, qui tamen de accepta gratia certi non sunt, & quidam ante mortis articulum certitudinem illam non assequuntur. Quod non fit quia circa veritatem promissionum divinarum haesitent, sed quia nimium spectant propriam indignitatem atque infirmitatem.