The psalmist reminds us in Psalm 43:5 that hope in God is foundational and essential for a healthy countenance. When we truly have hope in God, we will praise Him and demonstrate the joy of the Lord. To have less than joy leaves us in a place for spiritual refreshment. Matthew 5:16 gives us the "marching orders" to let our light shine so that others observe the Christlikeness of biblical behavior and thereby be brought to a place of giving glory to God. The very first reflection that the world sees is in our face. The set of our jaw, the eye contact we offer, the softness of our facial features or the presence of a pleasant smile contribute to a reflection of godliness. If those things are absent, then the opposite characteristics are often present, and our confidence has failed to reflect the image of Christ.
All of our motives and innermost thoughts and feelings ought to be screened through the glorious countenance of God's purity and holiness. As that becomes a continuing way of life, we will have a merry heart, and as a result, will demonstrate a cheerful countenance. God has made the way of life known to us, and our confidence is in His promise to make us full of joy with His countenance.
(c) 1993, 2007 NACollins Limited copy permission for 1 personal copy
taken from TOPICAL BIBLE STUDY MEDITATIONS , 2007 edition