Is there a dogmatic or theological (yet not dogmatic) justification for kneeling before a statue/icon of the Virgin Mary?

In one passage, we have the answer to the whole thing:

1 Chronicles 29:20 (DRB)

And David commanded all the assembly: Bless ye the Lord our God. And all the assembly blessed the Lord the God of their fathers: and they bowed themselves and worshipped God, and then the king.

In this culture and language, worship means a general service or demonstration of submission, not necessarily worship which exclusively denotes that you are serving God (i.e. which would indeed make it idolatry to do it to anyone else).

A similar passage in Ruth:

Ruth 2:10 (DRB)

She fell on her face and worshipping upon the ground, said to him: Whence cometh this to me, that I should find grace before thy eyes, and that thou shouldst vouchsafe to take notice of me a woman of another country?

This is comparable to Luke 1:43, where Elizabeth expresses thankfulness/unworthiness to be greeted by the mother of her Lord:

Luke 1:42-43 (DRB)

And she cried out with a loud voice, and said: Blessed art thou among women, and blessed is the fruit of thy womb. 43 And whence is this to me, that the mother of my Lord should come to me?

Bowing, kneeling (especially when in prayer anyway, and since Mary is considered Queen anyway) is not worship necessarily (in the sense we use the word today, i.e. 'worship only refers to service rendered to God').

In essence, 'worship' (in 'ye old' sense) can either be service of humility to a higher up or great person, be it of the authority or spiritually exemplar kind (or on our case, both, in reference to Mary), or it can be to God—but only the latter is sinful when given to creatures, and even then, the only difference between these two so-called 'worships' is the intent of the heart: 'Do I intend to serve this person as God? Or serve this fellow creature as a beloved, glorified member of the Body (and in this case, our Queen)?'

See my answer here for the statue issue, and the Church's teaching on such (issued just after the Council of Trent).

Short Answer

Theological & Dogmatic reference:(Summary)

1. Lumen Gentium 66

2. CCC966

3. Archangel Greetings bowing to Mary's Divine Motherhood. (Luke1:28)

4.The 4th Dogma of the Assumption

5. Other testimonies & revelation; i. Pre-Assumption Apparition, Ven. Mary of Agreda refer to Mary as "Queen of the Church. ii. St.James the Greater saw Mary "beheld by a great light" on a pedestal. iii. St. Therese of Liseaux said Mary is truly Queen of Heaven & Earth.

6. Biblical Reference (Revelation12:1)

7. Church Father teaching Mary is the First Tabernacle & the New Ark of the Covenant.

Explanation :

The simple answer is the people in the Old Testament know the customary greetings to a King and Queen.

Human showing highest respect for the King & Queen of this world show it by physical gestures of bowing and kneeling.

We are not talking of ordinary King & Queen here.

Mary is the Mother of the King of Kings.

The Catholic Church acknowledge Mary as Sovereign Queen of Angels, Queen of Heaven & Earth.CCC966

966 "Finally the Immaculate Virgin, preserved free from all stain of original sin, when the course of her earthly life was finished, was taken up body and soul into heavenly glory, and exalted by the Lord as Queen over all things, so that she might be the more fully conformed to her Son, the Lord of lords and conqueror of sin and death."508 The Assumption of the Blessed Virgin is a singular participation in her Son's Resurrection and an anticipation of the resurrection of other Christians:

The key word is Mary is "exalted". How high is Mary's exaltation?

“Placed by the grace of God, as God’s Mother, next to her Son, and exalted above all angels and men, Mary intervened in the mysteries of Christ and is justly honored by a special cult in the Church.” (LG, 66).

An Archangel who belong to Choir of Cherubim who knows the "secrets of God" showed us how to greet a Queen Mother in Luke1:28.

Douay-Rheims Bible

And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women.

Archangel Gabriel was sent to deliver a message only to the Theotokos. The greetings of HAIL! Full of Grace reveals that Angel Gabriel saw the state of soul of Mary and by virtue of understanding the message of God in fullness, Angel Gabriel knows the meaning of Mary becoming the Mother of the King of Kings and Lord of Lords, had to acknowledged the awesome majesty of the Queen Mother and had to bowed down.

In this Mary was troubled, She doesn't know that the state of Her soul was "full of grace" only an angel can see that. But the greatest mystery is, there's one fallen angel who is also a Cherub seeing his fellow Archangel bowed down realized he must bowed down too. Genesis3:15 comes again to satan's mind and fear engulfs his very being.

Genesis 3:15 Douay-Rheims 1899 American Edition (DRA)

"I will put enmities between thee and the woman, and thy seed and her seed: she shall crush thy head, and thou shalt lie in wait for her heel."

Mary became the First Tabernacle of God. Her Most Pure Womb in the Book of Kings exclaimed "The highest heavens cannot contain of God whom you carried in your womb".

Would you kneel before the Tabernacle of God, the New Ark of the Covenant?

The 4th Dogma of Assumption, the Catholic Church proclaims Mary as the Sovereign Queen of all. Sovereign Queen of Heaven & Earth.

Mary's "Pre-Assumption Apparition" the first Marian Apparition acknowledge by the Church to St.James the Greater in year 40AD while still living showed Mary already is exalted in a glorified form. The Woman is now standing on a pedestal a jasper column higher than all men and sorrounded by angels.

St James narration is an apparition and not a bilocation. Why? A bilocation is attributed to the saints who appears in their usual physical form. But Mary appeared in a "ghost like" form ,in the words of Ven.Mary of Agreda "beheld by a great light" . St.James the Greater saw Jesus "resurrected body" so he can attest the similarities of Mary's appearance to Jesus.

For full story of "Our Lady of the Pillar Apparition"

Venerable Maria of Agreda who was shown the life of the Blessed Virgin Mary in detail, writes in her Mystical City of God that St. James, brother of St. John, whom Our Lord called “Sons of Thunder”, had a special devotion to the Blessed Mother. Becoming the apostle of what today is Spain, Saint James was having a hard time evangelizing the northern region of Zaragoza. One night, as he prayed asking help for his plight, he suddenly beheld a great light in the midst of which he saw Our Lady surrounded by a multitude of angels.

The interesting thing is that Mary was still living in Jerusalem at the time. But as queen of the Church, she was given to see all that concerned her Son’s work, and being shown the prayer of her devotee, had obtained from Jesus to help him in a special way.

On learning of their lady’s wishes, the angels in her retinue promptly built a throne of luminous clouds on which they sat their queen, and swiftly carried her across the Mediterranean, serenading her all the way.

So now, the Blessed Mother consoled her son James, and assured him help for his endeavors. She asked him to build a shrine on the spot she appeared, and as a token of her help to the region, left a marble column or pillar topped by a small statue of herself holding her Infant Son.

By the pillar, she left an angel to ensure the safety of the holy image until the end of time. According to ancient Spanish tradition, this apparition occurred on January 2nd, 40AD. - The Marvelous Story Of Our Lady of the Pillar

Now this is only here on earth, noticed the wordings Ven.Agreda she called the Blessed Virgin Mary "Queen of the Church".

And the Church teaches that Mary is the Woman in the Revelation12:1

"* 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."

Mary is the Sovereign Queen of Heaven & Earth.

Now, knowing how the Old Testament people give reverence to the earthly King and Queen and by no less than an Archangel bowing to the Blessed Virgin Mary.Would it be fitting to bow and kneel before the Sovereign Queen the Mother of our Saviour, the King of Kings?

But in my posted comment I said, if you knew "who Mary is" in the eyes of God She deserves more than kneeling. She deserves our deepest gratitude and love acknowledging Her role as our "spiritual Mother"

Why? Jesus gave Mary to us as a gift, Jesus agonizing At the Foot of the Cross experience the great love & sacrifices of the Blessed Mother "from womb to tomb".Mary "still standing" did not abandon his beloved son in the greatest hour of sufferings. Mary had experience the greatest sorrows no earthly Mother can endure seeing His beloved son immolated.

Jesus precious last words to us pointed that more than kneeling to the Sovereign Queen, we must all BEHOLD Mary as our spiritual Mother. Jesus wants us to welcome Mary in our homes and especially into our hearts.

"Son Behold you Mother"(John19:27)

CCC969 "This motherhood of Mary in the order of grace continues uninterruptedly from the consent which she loyally gave at the Annunciation and which she sustained without wavering beneath the cross, until the eternal fulfillment of all the elect. Taken up to heaven she did not lay aside this saving office but by her manifold intercession continues to bring us the gifts of eternal salvation . . . . Therefore the Blessed Virgin is invoked in the Church under the titles of Advocate, Helper, Benefactress, and Mediatrix."512

"Mary is more Mother than Queen"

“It is true that Our Lady is Queen of Heaven and earth, but at the same time she is more Mother than Queen.” – St. Therese of Lisieux

It was also attested by the Patristic Fathers in the 1st Century Mary's two important title of inscription " Theotokos & Boetheia "

Patristic origins

There are two inscriptions of the first centuries of Christianity in Greek related to the Virgin Mary: : θεοτοκος (Teotokos, Theotokos, Mother of God) and βοηθεια (Boetheia, the Helper). The Fathers of the Church referred to Mary as "βοηθεια". John Chrysostom used the title in a homily of 345, Proclus in 476 and Sebas of Caesarea in 532. After the Patristic period (5th century), other persons used it like Romanos the Melodist in 518, the Patriarch of Jerusalem, Sophronius in 560, John of Damascus in 749 and German of Constantinople in 733.

In the view of Fr. Johann G. Roten, SM, the invocation of Mary as Help of Christians is part of the oldest prayer addressed directly to Mary, the Sub tuum praesidium, which was found on a papyrus dating, at the latest, from the end of the 3rd century. Praesidium is translated as "an assistance given in time of war by fresh troops in a strong manner." - Mary Help of Christians (Wikipedia)

I like to focus on the Greek word Boetheia,the Helper.

Boēthos is a noun made up of two words which mean (i) “cry out” and (ii) “run”. The related verb boētheō means “come to the rescue” or “supply urgently needed help”. (From HELPS word-studies.) Perschbacher gives the meaning of boētheō as “to run to the aid of those who cry out for help . . . “[2]

The following is every verse in the New Testament where boēthos and its cognates appear[3]:

In Matthew 15:25 and Mark 9:22-24, boēth– words are used where people were crying out to Jesus for help.

In Acts 16:9, 21:28, 27:17 and Revelation 12:16, boēth– words are used where strong help and support were required.

In 2 Corinthians 6:2, Hebrews 2:18, 4:16 and 13:6, boēth– words are used in the context of receiving divine help. - “A Suitable Helper” (in the Septuagint)

Apostolic and Patristic recognition in the first century of Christianity gave Mary the title Mary Help of Christians.

Now if you knew that Mary is the "Helper" the one who will run to your aid when you cry out for help, is kneeling enough?

As St. Peter run to Mary when he was caught in deep despair, and St.James the Greater called unto Mary too when caught in desolation.If we knew Mary is our Helper what gestures is appropriate, a physical gesture only? or will it involves our very heart acknowledging our deepest gratitude to Her as our Spiritual Mother.

St. Lukes had painted a Miraculous Image of Mary in the first century too the title of the paint attributed to Mary is the "Advocata Nostra".

From Apostolic to Church Father acknowledged Mary as our Helper,Theotokos and Advocate not to mentioned Her numerous titles.

Are we going to wait for the Fifth Dogma to be proclaim before we gave Mary the proper veneration and gratitude She rightfully deserves here on earth?

The Catholic Church like Mary is a humble church, it will wait for God's timing in bestowing Her a title that will be bind in Heaven. As we all know God's timing is always perfect.

Mary is our Co-Redemtrix, Advocate and Mediatrix.

We must not only express our deepest gratitude in physical gestures but most especially our reverence must come too, deeply in our hearts.