In Bible School I had a teacher who was so concerned with people watering down or outright denying the truth of Christ’s literal reign as king on the earth after His Second Coming that he considered it wrong to refer to Christ as king in this present age, biblical examples and numerous popular hymns and praise songs notwithstanding.
But I believe he had it wrong, and that of course we may acclaim Christ as King even today, and for this reason I love the Feast of Christ the King which is celebrated on the last Sunday of the church year, the Sunday next before Advent, which this year is November 20.
Christ the King is originally a relatively recent Catholic feast, introduced 1925 by Pope Pius XI. It moved to its current place in the calendar in the course of the post-Vatican II liturgical reforms in the Catholic Church and found its way into the calendars of several Protestant churches in the English-speaking world through the Revised Common Lectionary (RCL), an ecumenical, three-year lectionary which is an expanded adaptation of the Catholic Ordo Lectionum Missae lectionary for Sundays and feast days.
In the German-speaking world where I live the RCL is virtually unknown, with Protestant churches either following their own lectionaries (Lutherans, Reformed) or rejecting the idea of a lectionary altogether; for this reason Protestants in Austria, Germany and Switzerland don’t observe Christ the King Sunday — which is a shame, in my view. Instead, this Sunday is known as Eternity Sunday and focuses on commemorating the dead.
However, if and when we do acclaim and celebrate Christ as King we ought to call to mind what this actually means. Here is an excerpt from Pope Pius XI’s encyclical Quas Primas in which he promulgated this feast:
If to Christ our Lord is given all power in heaven and on earth; if all men, purchased by his precious blood, are by a new right subjected to his dominion; if this power embraces all men, it must be clear that not one of our faculties is exempt from his empire. He must reign in our minds, which should assent with perfect submission and firm belief to revealed truths and to the doctrines of Christ. He must reign in our wills, which should obey the laws and precepts of God. He must reign in our hearts, which should spurn natural desires and love God above all things, and cleave to him alone. He must reign in our bodies and in our members, which should serve as instruments for the interior sanctification of our souls, or to use the words of the Apostle Paul, as instruments of justice unto God. 
All these are truths which all too often we don’t want to hear, both with regard to our personal lives and in the context of our churches of all traditions; it is all the more important therefore to call them to mind and to acclaim Christ as King on this last Sunday of the church year.__________