The thematic orientation of the windows of the nave, from the rear to the front, is as follows. On the left, the three windows were created to highlight the themes of (1) world mission, (2) St. Peter and (3) the call of Simon Peter and Andrew. On the right, the windows celebrate (1) world peace, (2) the law of Moses and (3) music and King David.
Many marine details, including sea birds, fish and boats, appear on these windows. A discerning viewer can find Rockport's Motif Number One. Look for the lobster, too. It was added because of the lobster stew dinners that helped to establish funding for the music window.
On the right-hand wall hangs the bas-relief "Orante," another work by Walker Hancock. The piece, executed in 1927, depicts Christ with two adoring angels.
The three windows of the chancel opposite the organ pipes are the oldest in the building and were designed and executed by Oliver Smith, a local artisan. The largest of them presents The Blessed Virgin with Child in majestic color and form. Below the Madonna is a stylized picture of the nativity with the adoration by shepherds and angels. Flanking this dominant window are two smaller windows – the oldest depicting piety and charity. The zealous devotion of the boy Samuel is the subject of one. The outpouring of love is the subject of the other; it features the Good Shepherd and the Good Samaritan.
The dramatic reredos, created by sculptor Morgan Faulds Pike, was installed behind the altar in 2016. The cabinet, built by John E. Schreiner, is made of quarter-sawn white oak. The doors are dramatically closed at the end of the Good Friday service, to conceal the carved panels, and are reopened at the Easter proclamation during the Great Vigil of Easter. The three panels--Nativity, Crucifixion, and Road to Emmaus--are carved in linden wood. They reflect the style of an important school of sculptors, contemporaries of Albrecht Dürer, who worked in Bavaria during the late 15th and early 16th centuries. In 1994, Pike did extensive research in Germany to study the work of Tilman Riemenschneider (1460-1531), who was the most important of these artists. Pike’s use of expressive drapery and her graphically dramatic composition in the carved panels are directly influenced by Riemenschneider’s work. As sculpture created in the 21st century, the reredos reflects a contemporary sensibility, particularly in terms of how it highlights women’s importance in the biblical narratives and Pike’s respect for animals and the natural world. In the Road to Emmaus panel one of the two disciples is a woman. The crucifixion panel emphasizes the women at the foot of the cross, and Mary, mother of Jesus, is central in the Nativity panel. In that same Nativity panel, Pike surrounds the holy family with animals who are dignified witnesses to the birth of Jesus.
The wooden altar’s bold symbols include the alpha and the omega: "I am the alpha and the omega, the beginning and the end, the first and the last" (Revelation 22:13).
On either side of the altar are the most recent of St. Mary's stained-glass windows. To the right of the communion rail is a window that was originally intended for a side chapel. It presents a collage of the Parables of Jesus and deserves careful study as it tests the biblical scholar's acquaintance with the teaching stories of Christ.
The sanctuary candle burns above constantly and signals the presence of Christ. Parishioners support the burning of the sanctuary candle in memory of departed family members and friends.
On the wall to the left of the altar is the aumbry where the Blessed Sacrament is reserved. This handsome piece – carved of wood with a surface of gesso and silver leaf – is the work of the late Max Kuehne.
The organ is a 1947 Möller selected for the church by the world-renowned musician and St. Mary's summer organist, T. Tertius Noble. In the 1960s, parishioner and noted organ-builder Charles B. Fisk re-voiced two ranks of pipes in the Möller organ.
The pulpit was given in memory of Kenneth Brown by his mother. It was designed and constructed by Gloucester's Charles Nazarian utilizing six panels of a pulpit originally carved for another church by I. Kirchemayer, one of America's finest ecclesiastical carvers. There are 13 lancets, each one ornamented with a shield bearing a polychromed instrument of the Passion. The wrought iron lectern features a central motif of the Celtic cross.