9 For with
thee is the fountain [maqowr] of life [chay]: in thy
light ['owr] shall we see [ra'ah] light ['owr]. KJV-Interlinear
9 For with
you is the fountain of life; in your light do we see light. ESV
Christ is God, and God is the original fountain, from which all life flows. If you choose to reject Christ, then you in effect choose non-existence. If you choose to ignore Christ, then you in effect choose to know nothing, because Christ is truth and refusing to learn truth means learning nothing.
If anything exists, then it came from God originally. Where God is not involved, then the false, the lies, the non-existence is.
Thus, a relationship with God is the pre-requisite for having a life after this life, in eternity. And Gods rules are, access to Him is through faith in Christ, and by no other means.
Thus knowledge of doctrine is a pre-requisite for having knowledge, understanding, orientation, wisdom for life. And Gods rules are, that you must learn through instruction, which is a very simple task, while in fellowship, which is a very simple process, in order to grow up in your spiritual life.
Gods light is truth.
Our access to light is Bible doctrine.
And when we learn doctrine, then we see light, which simply means that we can see and understand what life is all about and why it is, what it is, and where it is going and how we fit in to everything.