Advent, which stems from the Latin adventus ("coming") is a time for Christians to contemplate both Christ's first coming to the world as baby and his return in glory. It's also a time to reflect on important foundations of the Christian faith, including the Incarnation and the Virgin Birth.
Lent marks a 40-day period on the church calendar leading up to the celebration of Easter. During Lent, Christians have traditionally engaged in practices of self-denial, like fasting, meant to orient their hearts and minds to the sufferings of Christ, who spent 40 days in the desert fasting and enduring temptations from Satan. While many evangelicals reject Lenten disciplines for their associations with Catholicism, in recent years a greater number have experimented with practices like giving up a favorite indulgence or abstaining from meat on Fridays.
Today's Thanksgiving feast has its origins in an English Reformation tradition carried on by the pilgrims who arrived at Plymouth in 1620. In an affront to the Catholic liturgical calendar, Puritans celebrated days of fasting and days of feasting—notably the day of feasting at the end of the fall harvest—in gratitude for God's provision. In an age where consumption of food is often far removed from fields where it is produced, a growing number of evangelicals have reinterpreted the holiday as a time not only to thank God for abundance, but to examine where abundance comes from and the ethics of food, hunger, and environment.