Today is the first Sunday in Advent. Not everyone understands what to think about and do during Advent. There are still plenty of Presbyterians who think Christmas is pagan or some sort of compromise with Roman Catholicism.
Here's a simple catechism I wrote last year (for children) explaining the Church Year and Advent.
The Church Year
Q 1. Why do we have different seasons of the year?
A. God created the seasons for man’s use and enjoyment.
Q 2. What do Fall and Winter remind us of?
A. Fall and Winter remind us of sin and death because it is dark and cold.
Q 3. What do Spring and Summer teach us?
A. Spring teaches us that God brings light and life to the world through Jesus Christ.
Q 4. What does the church calendar chiefly celebrate?
A. The church calendar celebrates the life of our Lord Jesus Christ.
Q 5. Why does the church have her own seasons?
A. The church has her own seasons to teach the world that true life is found in Jesus Christ and to resist reducing life to politics and economics.
Q 6. How are we to sanctify the seasons that God created for our benefit?
A. According to 1 Timothy 4:5, we are to set apart the seasons with the Word of God and prayer.
Q 7. How has the church set apart the seasons with the Word of God and prayer?
A. The church has chosen readings from the Old and New Testaments for each season and has ordered the prayer life of the church to match the life of Jesus.
Advent & Christmas
Q 8. What does the word “Advent” mean?
A. The word “advent” means “to come” and has to do with the coming of Jesus.
Q 9. What portion of the life of Jesus does Advent celebrate?
A. Advent celebrates the times leading up to the birth of Jesus as well as his coming again at the last day.
Q 10. How many Sundays are there in Advent?
A. There are four Sundays in Advent.
Q 11. What are the colors for Advent and what do they mean?
A. The colors for Advent are purple and royal blue. They remind us that Jesus is a glorious King.
Q 12. What do we pray for during Advent season?
A. During Advent we pray that Jesus our King would continue to come to us and serve us as he has promised.
Q 13. In our Advent prayers are we pretending that Jesus has not yet been born?
A. No. During Advent we are praying for him to come to us again and again as he has promised.
Q. 14. How did God fulfill his promises to his people in the Hebrew Scriptures?
A. God fulfilled his promises by uniting himself to our human nature in his Son, who faithfully lived a perfect life of service, died the death we deserve, and was raised to life again as the new man, and all this for our salvation.
Q 15. How has Jesus promised to come to us today?
A. In many different ways—to be with us on Sunday for worship, to help us daily when we are in trouble, and at the end of the world to establish the new heavens and earth.