From 1925 to 1928, the fresco surrounding the high altar was created by Katherine McEwan, an English-American artist who at the time of the commission to create the fresco, had retired to Arizona. Being a good friend of George and Ellen Booth, she agreed and returned to Michigan to do her first fresco work. Her companion during the fresco work was her black cat who is represented at the base of the south wall under the piscina. 

A good starting point to look at McEwan’s fresco is the base on the east wall. At the base, McEwan presents words from the Epistle of Paul to the Ephesians: “He hath built his church on the foundation of the apostles and prophets.” These words are the key to understanding what she has illustrated on the wall. They also serve as a record of the building of the Church throughout the world, and to some extent, the influence of the world on the Church.

East Wall

This wall showcases the church in action on the left and the realm of ideas on the right. The design ascends from the earthly Church at the base to the celestial choirs above.

The Evangelists:

The haloed heroic figures at the base are evangelists: John and Mark are portrayed on the left of the altar and Luke and Matthew are seen on the right. Above the heroic figures at the base, on the left, are missionaries carrying the Gospel into distant lands. There is a Spanish padre preaching to the Indians; St. Augustine taking the Christian message to Anglo-Saxons; and a modern missionary bishop in the Philippines. Moving upward to the left of the bishop is a group, symbolic of the Church in settlement work, with a street preacher. Further up are the children being taken out of factories and a Christian of the future carrying a banner. Above him is another man that is holding a globe, which is a symbol of perfection.

The Realm of Ideas:

Above the Apostles, on the right, are Peter and Paul healing the blind man in the temple, and just above them, the early Christians selling all they had and gave to the poor. To the right is Paul’s vision of Christ and his conversion on the road to Damascus. A group of men of science is in the center above Paul. This leads to a suggestion of a new generation, which is symbolized by the mother bringing her child to an angel. Above the angel is a concept of the last man achieving his destiny in the figure of a child being held aloft by an angel.

Celestial Choirs:

Further up in the fresco are seven archangels. There are Michael and his sword in a group of four on the left, and Gabriel bearing a lily, which is a symbol of the Resurrection, in a group of three on the right. After the archangels, there are two rows of angels with musical instruments. The climax of this vast fresco is the heavenly host and the four beasts of the Apocalypse bowing down before the Lamb of God. Also visible in this section is Peter, the haloed figure to the left of the evangelist, with his staff and keys, and Andrew in a brown robe displaying the symbol of martyrdom. 

North Wall

The Apostles:

On the north wall to the right of the Bishop’s chair is Paul with his hand uplifted as though preaching and holding two epistles; Bartholomew, one of the twelve apostles, with a book; Phillip, the apostle wearing a green cape; James; and at the end, Thomas. Not every figure in the fresco is named.

Important Christian Narratives:

On the section of the wall above Bartholomew, several of the narratives illustrated are related to the nativity story. These depictions include the Magi with their gifts, camels and servants; our Lady and the Christ Child fleeing to Egypt on a burro with Joseph; Mary and Martha and the Three shepherds; and the horrible legend of the Slaughter of the Innocents ordered by King Herod.

Other narratives depicted in this area consist of St. George slaying the dragon; Crusaders bearing banners with members of the Children’s Crusade; and the walls of Jerusalem, which rise to magnificent heights to suggest the Heavenly City.

Book of Revelation:

Still higher are incidents from the biblical book revelation. They serve as a link between the Church on earth and the heavenly body. Above the Magi is the incident of John on the Isle of Patmos kneeling and receiving a book from the angel.

The seven angels pouring out their bowls of wrath on the evil beast before the Last Judgment can be seen above. At the top of the north wall are the supporters of the physical universe with the moon and the stars, one of which is holding a censor representing the spiral nebula. Opposite of these images are similar angels.

Incidents related to the biblical book revelation continue near the top of the south wall, with the Four Horsemen: Conquest on a white horse with a bow; War on a red horse with armor and sword; Famine on a black horse with scales; and Death on a pale horse, followed by Hell walking on foot. Similar to the north wall, the top of the south wall concludes with an angel motif.

South Wall

Heroic Figures:

Above the stone niche are three of the ten wise virgins with their lamps. To the right are: Simon in red with a reversed cross; Jude with a fish; Stephen, deacon and first martyr whose hands are filled with the stones of his martyrdom; and the youthful John the Baptist with his parents, Zacharias and Elizabeth.

The Early Church:

This group represents the development of liturgy in the Church. It begins with a depiction of Sebastian’s martyrdom: the saint is tied to a column and pierced with arrows while an angel holds the palm of victory overhead. Next to that depiction is Christopher bearing the burden of the world on his shoulders in the form of the Christ Child.

Notable Figures:

A bit below, to the right of the molding, are sisters giving to the poor as well as one of the loveliest groups in the fresco, Francis of Assisi preaching to the birds and animals; Anthony being tempted by a woman with cloven hooves; and lastly, Jerome, the translator of the Vulgate version of the Bible, and his lion.

Above these groups is the Church as a patron of the arts. This concept is represented by showing a scribe and two students, an architect with a model of a church building and an artist who is sketching the Four Horsemen as they pass. An ascetic of hermit is the only one besides the artist who sees above.