Immaculate Conception: Why was it necessary for our Salvation? According to many Catholic apologists, like Dr. Robert Sungenis,1 the dogma of the immaculate conception of Mary is not simply binding because it is a divinely revealed dogma, but according to them it is binding additionally because logically speaking without Mary being sinless Jesus could not accomplish the redemptive work in the first place.
What exactly do they mean by this?
The story goes like this, to save mankind Jesus had to be sinless. Therefore Mary had to be sinless to not pass on original sin. But then Protestant apologists just say &quot;the grace could have been given directly to Jesus&quot; or &quot;why wasn't the grace given to the mother and father of Mary, or even further back?&quot;

Accordingly, by the inspiration of the Holy Spirit, for the honor of
the Holy and undivided Trinity, for the glory and adornment of the
Virgin Mother of God, for the exaltation of the Catholic Faith, and
for the furtherance of the Catholic religion, by the authority of
Jesus Christ our Lord, of the Blessed Apostles Peter and Paul, and by
our own:
We declare, pronounce, and define that the doctrine which holds that
the most Blessed Virgin Mary, in the first instance of her conception,
by a singular grace and privilege granted by Almighty God, in view of
the merits of Jesus Christ, the Savior of the human race, was
preserved free from all stain of original sin, is a doctrine revealed
by God and therefore to be believed firmly and constantly by all the
faithful. Hence, if anyone shall dare -- which God forbid! -- to think
otherwise than as has been defined by us, let him know and understand
that he is condemned by his own judgment; that he has suffered
shipwreck in the faith; that he has separated from the unity of the
Church; and that, furthermore, by his own action he incurs the
penalties established by law if he should are to express in words or
writing or by any other outward means the errors he think in his
heart.”
Blessed Pope Pius IX, Ineffabilis Deus, 8 December 1854

Questions in formal form is as follows: Why was it necessary for the salvation plan to have specifically Mary the mother of Jesus be utterly without sin?

1. For example, in this video debate at 1:05:18 (&quot;because if she isn't sinless, she's going to produce a sinful Savior&quot;) and 1:13:00.
Was Mary's Immaculate Conception Absolutely Necessary for our Salvation?
Before I go on with my answer, I object to that fact that you claim that according to many Catholic apologists, like Dr. Robert Sungenis, the dogma of the immaculate conception of Mary is necessary for our salvation.
&quot;According to many Catholic apologists, like Dr. Robert Sungenis, the dogma of the Immaculate Conception of Mary is not simply binding because it is a divinely revealed dogma, but according to them it is binding additionally because logically speaking without Mary being sinless Jesus could not accomplish the redemptive work in the first place.&quot; Can someone please name a few Catholic theologians with this viewpoint. In 2008 his local bishop had instructed him to stop writing about Jews and to remove the name &quot;Catholic&quot; from his blog.
The short answer is no.
Our salvation was guarantied by Our lord Jesus Christ on the Cross.

The Catholic Church believes that it was not absolutely or intrinsically necessary for the Blessed Virgin Mary to be sinless; only fitting or appropriate (God making the choice).
Thus, even a dogmatic belief in the Immaculate Conception does not in any way impinge upon the Two Natures of Christ. We believe the Immaculate Conception happened, and are required to believe this, but we don't believe that it had to happen exactly as it did (in all possible worlds, etc.), in order for God to be God.
All the Immaculate Conception did was make Mary as Eve was before the Fall (precisely why the Church fathers often called her the Second Eve or New Eve): unfallen and sinless; not subject to original sin. As Cardinal Newman remarked: why is it considered such an extraordinary thing that God chose to simply make one person -- the Mother of God the Son, the Theotokos -- the way that all of us would have been, but for the Fall?
Fr. Ryan Erlenbush wrote on The New Theological Movement website (12-8-11):

And this is the great difference between Jesus and Mary: She required a special grace to preserve her from the stain of sin, but our Savior (by virtue of the Incarnation itself, and on account of his divinity) could not possibly have contracted the guilt or debt of original sin in any respect.


While our Blessed Lady, even though Immaculately Conceived, required a Redeemer (namely, her own Son, Christ Jesus), the Lord did not have any need of a Redeemer. No special grace was required (beyond that of the Incarnation itself) to keep the Christ Child from original sin – he could not possibly have contracted it.


In this sense, the dogma of the Immaculate Conception is seen to be fitting and true while (in itself) not absolutely necessary, but the sinlessness of the Lord Jesus is absolutely necessary and super-eminently fitting.

Was Mary's Immaculate Conception Absolutely Necessary?

St. Thomas Aquinas maintains that it was indeed possible for Our Lord Jesus Christ to have been born of sinful woman; Christ's glory would not have been diminished thereby. But, he states elsewhere, it would have been inappropriate:

God so prepares and endows those, whom He chooses for some particular office, that they are rendered capable of fulfilling it, according to 2 Cor. 3:6: &quot;(Who) hath made us fit ministers of the New Testament.&quot; Now the Blessed Virgin was chosen by God to be His Mother. Therefore there can be no doubt that God, by His grace, made her worthy of that office. ... But she would not have been worthy to be the Mother of God, if she had ever sinned. First, because the honor of the parents reflects on the child, according to Prov. 17:6: &quot;The glory of children are their fathers&quot;: and consequently, on the other hand, the Mother's shame would have reflected on her Son. Secondly, because of the singular affinity between her and Christ, who took flesh from her: and it is written (2 Cor. 6:15): &quot;What concord hath Christ with Belial?&quot; Thirdly, because of the singular manner in which the Son of God, who is the &quot;Divine Wisdom&quot; (1 Cor. 1:24) dwelt in her, not only in her soul but in her womb. And it is written (Wis. 1:4): &quot;Wisdom will not enter into a malicious soul, nor dwell in a body subject to sins.&quot;
We must therefore confess simply that the Blessed Virgin committed no actual sin, neither mortal nor venial; so that what is written (Cant 4:7) is fulfilled: &quot;Thou art all fair, O my love, and there is not a spot in thee,&quot; etc. - Was the dogma of the Immaculate Conception formulated in response to someone challenging Mary's ability to bear a perfect Son?

If God preserved Mary from all sin, He could have preserved Christ's body and soul likewise without the grace of Mary's Immaculate Conception.

Was it necessary for God to make Mary immaculate at her conception so that she could be Jesus' mother?
No. The Church only speaks of the Immaculate Conception as something that was &quot;fitting,&quot; something that made Mary a &quot;fit habitation&quot; (i.e., suitable dwelling) for the Son of God, not something that was necessary.

And hence they [the Church Fathers] affirmed that the Blessed Virgin was, through grace, entirely free from every stain of sin, and from all corruption of body, soul and mind; that she was always united with God and joined to him by an eternal covenant; that she was never in darkness but always in light; and that, therefore, she was entirely a fit habitation for Christ, not because of the state of her body, but because of her original grace. . . .


For it was certainly not fitting that this vessel of election should be wounded by the common injuries, since she, differing so much from the others, had only nature in common with them, not sin. In fact, it was quite fitting that, as the Only-Begotten has a Father in heaven, whom the Seraphim extol as thrice holy, so he should have a Mother on earth who would never be without the splendor of holiness [Ineffabilis Deus].


Can anyone show where in Pope Pius IX's Papal Encyclical Ineffabilis Deus that the Mary's Immaculate Conception was absolutely necessary for our salvation. You can not!
Unless one can show evidence to the contrary, in Pope Pius IX's dogmatic definition of the Immaculate Conception that the Immaculate Conception of the Ever Virgin Mary was necessary for our salvation, the contrary is to be upheld.
St. Thomas Aquinas in his Summa clearly states that it was Adam and not Eve that was responsible  for the transition of original sin. Now if Mary, the Mother of Jesus is the New Eve and Jesus Christ is the New Adam, it is obvious that the Immaculate Conception was not necessary for our salvation for the Holy Spirit can operate in that dwelling place He so chooses to. It the Holy Spirit that made it possible for Christ to be free of original sin and not Mary, the New Eve.

The solution of this question is made clear by what has been said. For it has been stated that original sin is transmitted by the first parent in so far as he is the mover in the begetting of his children: wherefore it has been said that if anyone were begotten materially only, of human flesh, they would not contract original sin. Now it is evident that in the opinion of philosophers, the active principle of generation is from the father, while the mother provides the matter. Therefore original sin, is contracted, not from the mother, but from the father: so that, accordingly, if Eve, and not Adam, had sinned, their children would not contract original sin: whereas, if Adam, and not Eve, had sinned, they would contract it. - Whether if Eve, and not Adam, had sinned, their children would have contracted original sin?