In John 5:35, Jesus called John the Baptizer a burning and shining lamp. Significantly, John was called by the Greek word luchnos, translated shining lamp. Luchnos means a portable lamp or other direct illuminator, literally or figuratively.
On the other hand, the followers of the New Testament are referred to by the Greek word phos.
So phos means to shine or make manifest, especially by rays. It also implies luminousness (in the broadest application, natural or artificial, abstract or concrete, literal or figurative). So we are the light of the world, and we are to shine and make manifest, meaning live God's way of life.
This affirms that John (the Baptizer) came to shed light on a specific event - the coming of the Son of God. However, members of God's church are to shine and make visible God's entire way of life. So we must be shining witnesses by living God's way of life and teaching others about it as well.