Christ’s call for us to be salt and light is not an impossible one. In keeping with New Testament ethics, Jesus first tells us what we are and then calls us to live up to that standard. In Him we are salt and light (Matt. 5:13–16), and so we are to live out by faith what He has made us to be. If you are discouraged by your saltlessness or darkness, remember that Jesus declares you to be salt and light and press on, knowing that by the power of the Spirit you can obey His charge.
For further study:
The Bible in a year: