'Certainty' in the Bible

This hope [this confident assurance] we have as an anchor of the soul [it cannot slip and it cannot break down under whatever pressure bears upon it]—a safe and steadfast hope that enters within the veil [of the heavenly temple, that most Holy Place in which the very presence of God dwells],

Now faith is the assurance that what we hope for will come about and the certainty that what we cannot see exists.