A well known Catholic apologist recently characterized the Feast of the Assumption as that which is "best known to Evangelicals and Fundamentalists as 'the Marian dogma that isn't mentioned in Scripture'." He also rightly conceded: "it is true that Scripture nowhere mentions the Assumption--while noting the antiquity of the belief plus the fact that nothing in Scripture contradicts the Assumption."
The appeal to Tradition ("antiquity of the belief") and the fact that Scripture does not contradict the belief is standard apologetic fare when it comes to defending this dogma. However, I have never been able to make much headway with it.
Non-Catholic Christians pretty much tune out the Tradition argument because it falls into their standard "Catholic box of errors". In other words, they expect us to go there and by our "going there" their Catholic "mis-preconceptions" are reconfirmed.
Catholics should also understand that the Dogma of the Assumption is a favorite target not only because "it's not in Scripture", but also because it is a "Defined Dogma" (a Catholic MUST believe it and cannot hold otherwise). It is also the most recent "Defined Dogma" (Munificentissimus Deus, 1 November, 1950, Pope Pius XII) - thus it is fairly "fresh meat" for the antagonist.
I'm a great advocate of challenging the "it has to be in the Bible" but I have often wondered why we (Catholics) don't make more use of Scripture in the defense (and advocacy) of what the Catholic Church teaches when it is quite easy to do so.
As we know, Sacred Scripture and Sacred Tradition are not in conflict and everything the Church teaches (Tradition means "teaching") can be found either explicitly or implicitly in Scripture. However, there is little need to resort to the "implicit" when the "explicit" is readily available. And the Scriptural basis for the Assumption (I think) is actually quite "explicit".
Perhaps I can offer a little help with how to explain the Assumption to folks who do not accept the authority of Church, but who do accept only the "authority of Scripture".
The word "assumption" (small "a") means a thing supposed, a postulation, or proposition. The word derives from the Latin "assumere" which means "to take". The Ecclesiastical use of the word, with which we are concerned here, means a "taking into heaven".
Though the word "assumption" does not appear in Scripture (at least in the English versions), the act of a person being taken into heaven (assumed) does.
In Genesis 5:24 we read: "And Enoch walked with God: and he was not; for God took him." (KJV)
Here we see that Enoch was "taken", "assumed". Taken where? We have to "assume" that he was taken into heaven since Scripture states that he "walked with God". Even if you refuse to "assume" that Enoch was taken into heaven, you still have to admit that he was in fact "assumed", "taken".
In 2 Kings 2:11 we read about a better known instance of an "assumption": "And it came to pass, as they still went on, and talked, that, behold, there appeared a chariot of fire, and horses of fire, and parted them both asunder; and Elijah went up by a whirlwind into heaven." (KJV)
We don't have to wonder where Elijah was taken as we did with Enoch, for Scripture explicitly says where he went. We also have a confirmation that he was taken body and soul for we have an eye-witness: "And Elisha saw it, and he cried, My father, my father, the chariot of Israel, and the horsemen thereof. And he saw him no more…" (the very next verse)
Before we move on we should mention that there is also clear evidence for the assumption of a third Old Testament prophet. Though we don't have the clear reference to an "assumption" of Moses in Scripture as we do with Enoch and Elijah, we can be fairly sure that Moses was assumed otherwise it is difficult to explain how he came to be one of the two Prophets present at the Transfiguration (the other being Elijah - Matthew 17:1-9)
Note: There is also an ancient book entitled "Assumption of Moses" - a book that didn't make the cut for the Canon (books of the Bible) but is nevertheless thought to have been referenced in the canonical epistle of Jude. (Actually a discussion of this book and St. Jude's allusion to it, as well as his use of the Book of Henoch -another canon loser, bears on the whole issue of who got to decide what went into the Bible in the first place.)
So now to the Assumption of Mary. We have established that "assumption" has clear biblical precedent. The next step is to pose the question: If God could take Enoch and Elijah into Heaven, do you think he could have also taken Mary? The answer is of course, yes, since God can do anything. So the next question is: Do you think He would have wanted to?
1. There is biblical precedent for bodily assumption into heaven
2. God could have done the same for Mary that He did for Enoch and Elijah and given who she was, would have had greater reason to do so.
3. There is no evidence from Scripture or history that contradicts the assumption of Mary.
4. The belief in Mary’s assumption extends back to the earliest centuries of Christianity.
The Immaculate Conception
Happily, an honest look at the reality of Assumption of Mary in the Bible lays the foundation for an easy explanation, if not proof, of the other favorite target: the Dogma of the Immaculate Conception.
Having recounted the Biblical accounts of the Assumption in the cases of Enoch and Elijah the next question is "How is that Enoch and Elijah got to go to heaven before Christ died to open it?"
Enoch and Elijah were stained by original sin, "unclean", as was all mankind after the Fall. And since Revelations 21:27 tells us that nothing unclean shall enter heaven: "And there shall in no wise enter into it any thing that defileth…" (KJV), how did they get in?
We also know that the only way that one could be cleansed of the stain of original sin and restored to God's friendship would be through the merits of Christ's passion, death, and resurrection. But of course that hadn't happened yet.
So what to make of Enoch and Elijah? Is God not true to His word? Did He "cheat" in their case? Of course not. But how to reconcile? Catholicism offers the only available answer…an answer incarnated in the person of the Blessed Virgin Mary:
The Dogma of the Immaculate Conception holds that Mary was in fact "saved": ("I rejoice in God my Savior") from original sin at the moment of her conception. She was saved in the only way that she could be saved, as we all are saved, by the passion, death, & resurrection of Jesus. But that hadn't "happened yet" either.
The words "happened yet" are the key. As we know, God, being the creator of Time is not subject to it. As an eternal being there is no past or future for Him. All is an eternal present. So though for us the salvific mission of Jesus on earth happened at a particular point in historical time, the merits of that mission are not subject to historical time and can be applied by God as He wills.
This is the only way to explain how Enoch and Elijah could be taken up into Heaven to “walk with God". Since God's Word will "not be mocked", we have to acknowledge that Enoch and Elijah were "saved". And since the only way to be "saved" is through the merits of the Paschal Mystery; and since that Saving Event hadn't "happened yet" (in time), the only answer left us is that God, who is not subject to time, chose to apply those merits to Enoch and Elijah, which, in effect, meant that they were "pre-redeemed".
The Church hasn't defined this "pre-redemption" of Enoch and Elijah, but She has defined it in the case of the Blessed Virgin Mary. The saving merits of Christ's passion, death, and resurrection are applied to Mary by God at the moment of her conception.