The Christian calendar with seasons of Advent, Christmas, Epiphany, Ordinary, Lent, and Easter/Pentecost, Kingdomtide, is something that the Church developed over decades and centuries, but mostly after the days of Constantine when the Church gained civil freedoms from persecution and elevation into prominence in Roman society.  Advent, in particular, was not introduced until about the mid-6th century. 

While holding the important theme of Christ's powerful return, somewhat penitential and somewhat anticipatory, it is observed technically for 4 weeks before Christmas, but in reality it is mostly overshadowed by the joyful expectations as well as cultural pressures of celebrating Christmas and Christ's first appearance, especially in a secular materialistic society and obviously much more popular and theologically emphasized, concerning the importance of the incarnation. While I appreciate the liturgical calendar for several reasons, I do not idolize it, and can also see some negative effects it can have upon the lives of Christians living and thinking cyclically or compartmentalized as the Church in the world.

Considering how the early Church of the first 300 years lived in closer reality to the Great Commission with its accompanying persecution without a developed Church calendar, and how the hope and importance of Christ's return was sufficiently and necessarily emphasized in the apostle's writings, with healthy reminders concerning  both a coming judgement and salvation to balance out a beleiver's attitude and perspective during the remainder of their lives on earth, helping them to both endure wordly trials and live lives worthy of their heavenly callings, also nurturing a greater concern for the unsaved lost, I find that the compartmentalized mere 4 week seasonal focus on Christ's 2nd appearance just before Christmas, inadequately calls to mind for the Christian, the importance of this biblical Gospel truth with its dual themes, and the ongoing season that calls for an awareness of both the end of present age and the beginning of the new and everlasting Kingdom upon Christ's return, not as a newborn baby, but as a victorious, conquering, and glorifed King.