Let's level the playing field. Is there Scripture substantiation that every practice, devotion and doctrine must be substantially found in scripture to be valid? No, there isn't any. It's a man made Protestant tradition. Your premise is not in the Bible but you demand we play by your rules.
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Jesus ascended by His own power, but Our Lady was assumed by the power of her Son’s victory over death.
Catholics believe that all Catholic and Christian doctrines must be in
harmony with Scripture and must not contradict it. Some doctrines are able to be supported only indirectly, implicitly, or by deduction from other related Bible passages, but
all Catholic doctrines have scriptural support in some sense. We also believe in sacred tradition, itself always in harmony with Scripture. Sometimes (as in the present case), a doctrine is “stronger” in tradition.
I agree that there is no direct “proof” of Mary’s Assumption in Scripture, but
there is strong deductive and analogical evidence. The
deductive argument has to do with the “consequences” of Mary’s Immaculate Conception: a doctrine more directly indicated in Scripture (e.g., Lk 1:28).
Bodily death and decay are the result of sin and the fall of man (Gen 3:16-19; Ps 16:10), so it stands to reason that an absence of actual and original sin would allow for instant bodily resurrection. It’s
as if Mary goes back to before the fall (for this reason the Church fathers call her the “New Eve”).
Jesus’ resurrection makes possible the universal resurrection and redemption of our bodies as well as souls (1 Cor 15:13-16). Mary’s Assumption is the “first fruits,” sign, and type of the general resurrection of all (created) mankind; she exemplifies the age in which death and sin are conquered once and for all:
1 Corinthians 15:17-26
The
analogical argument is a second line of approach: biblical examples that have strong similarity in important respects to Mary’s bodily Assumption. Here are five such analogies:
2 Kings 2:1, 11:
2 Corinthians 12:2-3
1 Thessalonians 4:16-17
Hebrews 11:5
Revelation 11:11-12
In three of these instances, the person didn’t die (in one the person even came
back); in two they died first. The Church hasn’t declared whether Mary died or not. All of these events occur by virtue of the power of God, not the intrinsic ability of the persons.
Jesus ascended by His own power, but the Blessed Virgin Mary was assumed by the power of her Son Jesus’ victory over death. Hers was an “immediate resurrection.” One day
all who are saved will be bodily resurrected. Mary was the first after Jesus’ resurrection: quite appropriately (and even, I submit, “expected”), since she was Jesus’ own Mother.
http://mcn.aod.org/2016/10/catholics-believe-marys-bodily-assumption/
for further reading:
Bodily Assumption of Mary (John Saward: Protestant) [edited in 1994; Facebook]
Bodily Assumption of Mary (Blessed John Henry Cardinal Newman) [edited in 1994; Facebook]
Bodily Assumption of Mary (Archbishop Fulton Sheen) [edited in 1994; Facebook]
Assumption & Immaculate Conception: Part of Apostolic Tradition (vs. James White) [June 1996]
Mary’s Assumption: Brief Explanation, with a New (?) Biblical Parallel [3-1-07]
Mary’s Assumption vs. Material Sufficiency of Scripture? [4-22-07]
Mary’s Assumption & “Reformer” Heinrich Bullinger [4-6-08]
Mary’s Assumption & Historic Protestantism [6-30-08]
Immaculate Conception and Assumption: Why Defined So Late? [2-1-09]
11 Bible Passages & Mary’s Assumption [2009]
Defending Mary (Revelation 12 & Her Assumption) [5-28-12]
Is Mary’s Assumption Able to be Inferred from Scripture Alone? [8-14-15]
Bible on Mary’s Assumption [2015]
Mary’s Death
“Armstrong vs. Geisler” #7: Mary’s Assumption [3-1-17]
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Armstrong vs. Collins & Walls #6: Assumption, Queen Redux [10-19-17]
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Biblical Arguments in Support of Mary’s Assumption [
National Catholic Register, 8-15-18]