In the Bible, to know
is more than to understand with your brain. It often points to a relationship. To know
God means that you spend time with him. The opposite is also true: that when, in the time of the judges, it is said that the people forgot the Lord their God (Judges 3:7), it does not mean that he was gone from their minds, but that they just ignored him.
To know
God means that you entrust yourself in faith to him.
7 Je vous prendrai pour mon peuple, je serai votre Dieu, et vous saurez que c'est moi, l'Eternel, votre Dieu, qui vous affranchis des travaux dont vous chargent les Egyptiens.