'Certainty' in the Bible
Know with certainty that the Lord your God will not continue to drive these nations from before you; but they shall be a snare and trap to you, and a scourge in your sides and thorns in your eyes, until you perish from off this good land which the Lord your God has given you.
For on the day you go out and pass over the brook Kidron, know with certainty that you shall die; your blood shall be upon your own head.
And the king sent for Shimei and said to him, Did I not make you swear by the Lord and warn you, saying, Know with certainty, on the day you go out and walk abroad anywhere, you shall surely die? And you said to me, I have heard your word. It is accepted.
To make you know the certainty of the words of truth, that you may give a true answer to those who sent you?
But [in the midst of judgment there is the promise and the certainty of the Lord's deliverance and] there shall be no gloom for her who was in anguish. In the former time [the Lord] brought into contempt the land of Zebulun and the land of Naphtali, but in the latter time He will make it glorious, by the way of the Sea [of Galilee, the land] beyond the Jordan, Galilee of the nations.
The Lord has said to you, O remnant of Judah, Do not go to Egypt. Know for a certainty that I [Jeremiah] have warned and testified to you this day
Now therefore know for a certainty that you shall die by the sword, by famine, and by pestilence in the place [Egypt] where you desire to go to dwell temporarily.
The king answered, I know with certainty that you are trying to gain time, because you see the thing is gone from me and because you see that my word [against you] is sure:
[My purpose is] that you may know the full truth and understand with certainty and security against error the accounts (histories) and doctrines of the faith of which you have been informed and in which you have been orally instructed.
Knowing [with all certainty] that it is from the Lord [and not from men] that you will receive the inheritance which is your [real] reward. [The One Whom] you are actually serving [is] the Lord Christ (the Messiah).
For our [preaching of the] glad tidings (the Gospel) came to you not only in word, but also in [its own inherent] power and in the Holy Spirit and with great conviction and absolute certainty [on our part]. You know what kind of men we proved [ourselves] to be among you for your good.
[Now] we have this [hope] as a sure and steadfast anchor of the soul [it cannot slip and it cannot break down under whoever steps out upon it -- "a hope] that reaches farther and enters into [the very certainty of the Presence] within the veil,
So you also must be patient. Establish your hearts [strengthen and confirm them in the final certainty], for the coming of the Lord is very near.