Be sealed with the Holy Spirit.
CCC1304 Like Baptism which it completes, Confirmation is given only once, for it too imprints on the soul an indelible spiritual mark, the "character," which is the sign that Jesus Christ has marked a Christian with the seal of his Spirit by clothing him with power from on high so that he may be his witness.
A side note on "knowing better". The Bool of Revelation is a liturgical work (cf http://www.scotthahn.com/resources-1/2016/1/14/the-lambs-supper). Described in its pages is the liturgy of Heaven and earth. A disciple familiar with the Sacred Liturgy will recognize in its pages a tapestry of the ars celebrandi of salvation in Christ, replete with warnings of dangers and exhortations to persevere in the Faith and to persevere in the faithful celebration of Holy Mass. The visions confirm that we have one foot on earth and one foot in heaven. Saint John, speaking in liturgical "code" to those under severe persecution, knew his listeners would understand that he was encouraging them to keep the Faith by keeping the Liturgy undefiled and, by so doing, would keep their souls. Rather than buying and trading with the world to achieve the approval of the world, the Christian, sealed with the Blood of the Lamb, would pass beyond this world past oblivion and the absence (emptiness) of the devil to enjoy the fullness of life in Jesus Christ.
The soul, without the baptismal character of the redeemed in Christ and the strengthening of the Holy Ghost in Confirmation (con = with; firmatio = strength), risks compliance with the (fading) ruler of this world, the devil.
Of Feasts and Festivals
Pentecost: the fulfillment of the Law (now inscribed by the Holy Spirit upon the human heart). The Holy Spirit descended upon the Apostles and Mary
Passover and Easter. 7 (completeness) x 7 = 49, and the 50th.
The Hebrew word פּסח pesach (Strong's #6453) is the noun behind the word for 'Passover' and comes from the verb פּסח pâsach 'to pass over, spring/leap over' (Strong's #6452). From a numerological point of view and that of biblical neatness it is rather amazing that the word for probably the most important Jewish festival celebrating the Exodus redemption occurs exactly 49 times. Essentially 7x7, symbolic of perfection, a week of weeks leading up to a Pentecost (50 days later). Furthermore, the root verb occurs exactly 7 times. [S]
To thee do we cry, poor banished children of Eve. To thee do we send up our sighs, mourning and weeping in this valley of tears.