"For we live by faith, not by sight."
The Christian life is a life of faith. We hope for what is to come. We fix our eyes on all that is unseen. To live by sight is to be shortsighted. All that we can see revolves in this world, and we are not meant to take residence in this world. We are citizens of heaven. Our Father awaits up there. The rewards for our efforts and the Gospel of Christ are still ahead.
When we keep all these in mind, we understand what Paul exactly meant in 2 Corinthians 4:18. We look not to things that are seen, but to all that is unseen. We realize that all hardships, no matter how difficult and seemingly long they may be, are temporary. There is an end to suffering and pain. Better things are ahead. And because we live by faith not by sight, we will not lose heart. We will press on.
