To fellowship with God we walk in the light. (1Jn 1:7-8) What does this mean, to walk in the light?
Light enables us to see; we discern our environment as light reflects off of it. Similarly, God’s revelation in Creation (1Ti 6:20), in Scripture (Ps 119:105), and in Christ (Jn 8:12) enables us to see our spiritual world; as we meditate on 
Him in every circumstance of life, evaluating and discerning in light of God’s ways and laws, His truth reflects off all about us and enables us to see.
To walk in spiritual light then is to be aware of, inclined toward and aligned with truth, with God’s revelation in all its forms. It’s being honest and open with God, with facts, with science, with history, and with His Word — both Scripture and His Son — with all of reality, aligning ourselves with Him as best we can through truth … all truth.
It’s looking at all sides of every question without fear or bias, refusing to accept inconsistency and contradiction in our faith, prayerfully and humbly exploring every mystery, welcoming healthy debate and constructive criticism. It’s seeking Him as He is; not as we wish for Him to be.
Every lie we cherish becomes a stronghold of darkness; in neglecting truth we stumble away from God. He is light; in Him there’s no darkness at all. (1Jn 1:5) He invites us to come, to walk with Him in spirit and in truth, enjoying every moment with Him as a perfect gift. (Is 2:5)
As we ask God to reveal Himself in truth, He does; as we seek, we find; as we knock, the doors will open. (Mt 7:7-8) Buy the truth; let every place in our hearts and minds rejoice in His light. (Lk 11:36)