Come To Our Aid, O Lord!
In this Fourth Week of Advent, our final days of preparation before Christmas, we ask Christ to forgive us for our sins and, through His grace, to create us anew when He comes.

This week is also a time to recollect, to reflect on our Advent journey. If we have let the hustle and bustle of the season get in the way of our spiritual preparations for Christmas, we have one last chance to refocus—and the light of the candles on the Advent wreath can be a symbol of our focus, as well as a symbol of the light of Christ.

Traditionally, the prayers used for the Advent wreath for each week of Advent are the collects, or short prayers at the beginning of Mass, for the Sunday of Advent that begins that week. The text given here is of the collect for the Fourth Sunday of Advent from the Traditional Latin Mass; you could also use the Opening Prayer for the Fourth Sunday of Advent from the current missal. (They are essentially the same prayer, with different English translations.)

Advent Wreath Prayer for the Fourth Week of Advent

Bestir, O Lord, Thy might, we beseech Thee, and come; and with great power come to our aid, that, by the help of Thy grace, that which is hindered by our sins may be hastened by Thy merciful forgiveness. Who livest and reignest, with God the Father, in the unity of the Holy Ghost, God, world without end. Amen.

An Explanation of the Advent Wreath Prayer for the Fourth Week of Advent
In the Advent Wreath Prayer for the Third Week of Advent, we asked Christ to enlighten our minds through His grace. This week, we ask Him to grant us that same grace so that we can be prepared to accept the salvation that He brings to us through His Incarnation.

Definition of Words Used in the Advent Wreath Prayer for the Fourth Week of Advent
Bestir: to stir up, rouse, bring into action
Thy might: the power of God
Beseech: to ask with urgency, to beg, to implore
Great power: in this case, the grace that Christ offers us
Hindered: delayed or obstructed; in this case, our salvation is being prevented by our sins
Hastened: moved more quickly; in this case, the forgiveness offered by Christ can remove the obstacles to our salvation that our sins have created
Merciful forgiveness: forgiveness that is undeserved, because our sins merit punishment; Christ in His mercy offers forgiveness because He loves us, not because we have earned His forgiveness
Holy Ghost: another name for the Holy Spirit, less commonly used today than in the past