In Germany and in many countries that are influence by Christian tradition on Sundays by law the shops are closed, and it is a day where people in general don't work. According to the Jewish calendar Sunday is the first day of the week. It had been on a Sunday when Jesus rose from the dead. In the year 321 the Roman emperor Constantine declare the Sundays to be holidays in memory of the resurrection of Jesus. This also is the reason why in most Christian churches there are services on Sunday.
Since on Sundays people don't work and have time, Christmas markets are open on Sundays. After all this is good for business, and in our materialistic world this is extremely important.
But on the third Sunday in Advent we also light the third candle. Perhaps in spite of all hectic and shopping you will today find time to reflect upon Jesus and the light. This is what John writes about the light:
Yet I am writing you a new command; its truth is seen in him and in you, because the darkness is passing and the true light is already shining. (1. John 2,8 NIV)
Every afternoon the sun now sets earlier, and we have less light. But there are two kinds of light. There is the light that very realistically shows us the way so that we can see something and don't get lost in the darkness.
In the same way there also exists the inward light that shines in our hearts or doesn't. This light is Jesus. Jesus is not only the light that lightens the path for us. Jesus is the way himself, He is the path out of darkness out of the world of evil into the light, into the world of truth and good.
Inn order to find this way and in order to be rescued out of darkness and reach the world of God and of light, we human beings have to repent. Have a look at this page. Here everything is precisely being explained.