How can we call Mary the ‘Mother of God’?

Is it legitimate to call Mary the “Mother of God”? Some Christians reject the title, saying it implies that God himself somehow has his origin in Mary. How could the Creator of all things, who depends on no one else for his existence, possibly have a “mother”?

What is the liturgical calendar?

The liturgical calendar is omnipresent in Catholic life. Many parish bulletins list the liturgical days of the week and corresponding Scripture readings, but what is it?