Before electronic navigation was invented, airplane pilots had used airport beacon lights to find airports when flying at night. In fact, some small pleasure aircraft may still use the beacons. Likewise, ship captains for centuries used lighthouse beacons along the shore to help them navigate the dark nights.

Similarly, millennia ago God established a beacon that would help the people of this world find their way in a spiritually dark world.

On Mount Sinai, God established a special covenant concerning the Sabbath. He told Moses, "Speak also to the children of Israel, saying: ‘Surely My Sabbaths you shall keep, for it is a sign between Me and you throughout your generations, that you may know that I am the L ord who sanctifies you'... It is a sign between Me and the children of Israel forever" (Exodus 31:13, 17).

According to Strong's Concordance, the word translated "sign" can mean, among other things, a signal such as a beacon.

A beacon is a guiding or warning signal. Often it is an alternating light, such as the airport beacon that alternates between green and white every few seconds.

For those who are truly seeking God's way of life in this spiritually dark world, the Sabbath is like a beacon that alternates every seventh day of the week showing the way to Jesus Christ, the true light of the world, and to the true Church of God.