In the past 150 years, there have been only two dogmas regarding this issue that have been formally defined by the pope in an excathedral statement of papal infallibility. The first is the dogma of the Immaculate Conception in 1854, and the second is the dogma of the Assumption of Mary in 1950. An article of faith is usually defined in a solemn fashion in an excathedra statement because it is being denied, falsely represented, or attacked. Excathedra refers to the pope’s power of infallibility in matters of faith and morals given to him by the Holy Spirit upon his elevation to the chair of St. Peter. Cathedra means “seat,” hence the expression “from the chair of St. Peter.”
In these two instances, the belief in Mary’s Immaculate Conception and her Assumption into paradise were not attacked, but were commonly believed and taught since the time of the apostles. When Pope Pius IX defined Mary’s Immaculate Conception, however, it naturally flowed that her Assumption should also be defined.
In Revelation 12:1 we read, “A great sign appeared in the sky, a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars.” With these words, Pope Pius XII solemnly defined Mary’s Assumption for all generations. In this document the pope states that because Mary did not have original sin due to her Immaculate Conception, she did not have to suffer decay on earth. Instead, her divine Son, Jesus, assumed her body and soul into heaven. Ascension is different from Assumption. Ascension refers to Jesus ascending into heaven by His own power, because He is the Second Person of the Most Blessed Trinity. Assumption refers to the fact that someone had taken Mary into heaven; in other words, she could not do this herself. Of course, that someone is her Son, Jesus Christ.
The Assumption of Mary is also a feast of hope for members of Church militant— the faithful keeping up the fight of good against evil. Her Assumption prefigures our Resurrection of the body on the last day and subsequent Assumption into heaven when the world ends. The reward for Mary’s fidelity, humility, and obedience to God was her Assumption. Remember, it was original sin that brought death and separation about. It is therefore consoling for members of the Church to remain steadfast in belief and untiring in service to the Lord, like Mary did, so that we, too, may enjoy eternal bliss in heaven.