"Then said Jesus unto them, Yet a little while is the light with you. Walk while ye have the light, lest darkness come upon you: for he that walketh in darkness knoweth not whither he goeth. While ye have light, believe in the light, that ye may be the children of light…" (John 12:35, 36)
We should never take light for granted, especially spiritual light. There are some very sobering words in these verses and the next four. For instance: "…lest darkness come upon you"; "These things spake Jesus, and departed, and did hide himself from them."; "Therefore they could not believe". This is deadly important when your soul is at stake. Man's opportunity for salvation only comes as the "light of the glorious gospel of Christ" shines in his heart. The words of Jesus, "While ye have light, believe in the light," indicates there may come a time when you will be without it.
Looking beyond this, however, God lights our pathway through the Christian life, and the same warning applies. No one likes to walk in the dark. For one thing, it's dangerous, because, as Jesus says in verse 35, when you are walking in the dark, you never can never be sure where you are going. I've seen Christians like that. They stumble through life, fumbling around for God's will, and falling over every obstacle Satan puts in their way.
On the other hand, there is a blessed assurance—a spring in the step, if you will—when one is walking a well-lit path. Not only is the next step visible, but often the light spreads a few steps ahead. Not enough to render faith unnecessary, but enough to make panic unreasonable.
God has promised that His Word will be "a lamp unto our feet, and a light unto our path," but if we choose to veer out of the light, we should not be surprised when we suddenly find ourselves in the dark.
Light rejected brings greater darkness.