The doctrine of the Assumption says that at the end of her life on earth Mary was assumed, body and soul, into heaven, just as Enoch, Elijah, and perhaps others had been before her. It’s also necessary to keep in mind what the Assumption is not. Some people think Catholics believe Mary "ascended" into heaven. That’s not correct. Christ, by his own power, ascended into heaven. Mary was assumed or taken up into heaven by God. She didn’t do it under her own power.
The Church has never formally defined whether she died or not, and the integrity of the doctrine of the Assumption would not be impaired if she did not in fact die, but the almost universal consensus is that she did die. Pope Pius XII, in Munificentissimus Deus (1950), defined that Mary, "after the completion of her earthly life" (note the silence regarding her death), "was assumed body and soul into the glory of heaven."
The possibility of a bodily assumption before the Second Coming is suggested by Matthew 27:52–53: "[T]he tombs also were opened, and many bodies of the saints who had fallen asleep were raised, and coming out of the tombs after his resurrection they went into the holy city and appeared to many." Did all these Old Testament saints die and have to be buried all over again? There is no record of that, but it is recorded by early Church writers that they were assumed into heaven, or at least into that temporary state of rest and happiness often called "paradise," where the righteous people from the Old Testament era waited until Christ’s resurrection (cf. Luke 16:22, 23:43; Heb. 11:1–40; 1 Pet. 4:6), after which they were brought into the eternal bliss of heaven.
There is also what might be called the negative historical proof for Mary’s Assumption. It is easy to document that, from the first, Christians gave homage to saints, including many about whom we now know little or nothing. Cities vied for the title of the last resting place of the most famous saints. Rome, for example, houses the tombs of Peter and Paul, Peter’s tomb being under the high altar of St. Peter’s Basilica in Rome. In the early Christian centuries relics of saints were zealously guarded and highly prized. The bones of those martyred in the Coliseum, for instance, were quickly gathered up and preserved—there are many accounts of this in the biographies of those who gave their lives for the faith.
It is agreed upon that Mary ended her life in Jerusalem, or perhaps in Ephesus. However, neither those cities nor any other claimed her remains, though there are claims about possessing her (temporary) tomb. And why did no city claim the bones of Mary? Apparently because there weren’t any bones to claim, and people knew it. Here was Mary, certainly the most privileged of all the saints, certainly the most saintly, but we have no record of her bodily remains being venerated anywhere.
Complement to the Immaculate Conception
Over the centuries, the Fathers and the Doctors of the Church spoke often about the fittingness of the privilege of Mary’s Assumption. The speculative grounds considered include Mary’s freedom from sin, her Motherhood of God, her perpetual virginity, and—the key—her union with the salvific work of Christ.
The dogma is especially fitting when one examines the honor that was given to the ark of the covenant. It contained the manna (bread from heaven), stone tablets of the ten commandments (the word of God), and the staff of Aaron (a symbol of Israel’s high priesthood). Because of its contents, it was made of incorruptible wood, and Psalm 132:8 said, "Arise, O Lord, and go to thy resting place, thou and the ark of thy might." If this vessel was given such honor, how much more should Mary be kept from corruption, since she is the new ark—who carried the real bread from heaven, the Word of God, and the high priest of the New Covenant, Jesus Christ.
Some argue that the new ark is not Mary, but the body of Jesus. Even if this were the case, it is worth noting that 1 Chronicles 15:14 records that the persons who bore the ark were to be sanctified. There would be no sense in sanctifying men who carried a box, and not sanctifying the womb who carried God himself! After all, wisdom will not dwell "in a body under debt of sin" (Wis. 1:4 NAB).
But there is more than just fittingness. After all, if Mary is immaculately conceived, then it would follow that she would not suffer the corruption in the grave, which is a consequence of sin [Gen. 3:17, 19].
Mary freely and actively cooperated in a unique way with God’s plan of salvation (Luke 1:38; Gal. 4:4). Like any mother, she was never separated from the suffering of her Son (Luke 2:35), and Scripture promises that those who share in the sufferings of Christ will share in his glory (Rom. 8:17). Since she suffered a unique interior martyrdom, it is appropriate that Jesus would honor her with a unique glory.
All Christians believe that one day we will all be raised in a glorious form and then caught up and rendered immaculate to be with Jesus forever (1 Thess. 4:17; Rev. 21:27). As the first person to say "yes" to the good news of Jesus (Luke 1:38), Mary is in a sense the prototypical Christian, and received early the blessings we will all one day be given.
The Bible Only?
Since the Immaculate Conception and Assumption are not explicit in Scripture, Fundamentalists conclude that the doctrines are false. Here, of course, we get into an entirely separate matter, the question of sola scriptura, or the Protestant "Bible only" theory. There is no room in this tract to consider that idea. Let it just be said that if the position of the Catholic Church is true, then the notion of sola scriptura is false. There is then no problem with the Church officially defining a doctrine which is not explicitly in Scripture, so long as it is not in contradiction to Scripture.
The Catholic Church was commissioned by Christ to teach all nations and to teach them infallibly—guided, as he promised, by the Holy Spirit until the end of the world (John 14:26, 16:13). The mere fact that the Church teaches that something is definitely true is a guarantee that it is true (cf. Matt. 28:18-20, Luke 10:16, 1 Tim. 3:15).