On the chancel floor the mosaics portray an olive branch, representing the entry of Jesus into Jerusalem when the crowds waved palm branches, a peacock, three fish, a crown, a lily, a lion and a hart. Over the arch on the north side are angels of praise with trumpets and bells. On the south side above the organ there are angels with sword and olive branch, and orb and cross, representing the Kingship of Christ. The panelled ceiling is painted with a rich variety of decorative patterns and Christian symbols.  
 
The Sanctuary steps are of coloured marble, the altar and reredos of white pavanozza marble. The altar table is a solid block of marble ten feet long and carved with great skill. The veins in marble make it notoriously difficult to work, with the constant danger of the material splitting along the veins. It is a tribute to the local craftsmen employed that they could produce such deep and detailed work. The altar was displayed at the Newcastle Royal Jubilee Exhibition of 1887. (The pulpit and altar were part of Messr. Emley & Sons stand).  
 
Above the altar are three mosaic figures, to the design of Charles William Mitchell. In the centre is a figure of the risen Christ with the Greek letters A and Ω - Alpha and Omega, the beginning and the end. To the left of the central figure stands St Gabriel the Messenger and to the right St Michael the Archangel; these figures were also designed by the younger Mitchell who became the patron of the Living on the death of his father in 1895.

The text above the altar and below the figures reads in Latin: 'Glory to the Father, and to the Son, and to the Holy Ghost.'

The east window illustrates the Birth of Our Lord, with the visitation of the Shepherds and Wise Men. The east window is a collaborative effort by Spence (the decorative work) and J.W. Brown (the figure scenes), the design for this window appears also to have been shown at the 1887 exhibition.

The vitreous glass wall mosaics, designed by Spence and C.W. Mitchell, and executed by Messrs. Rust & Co. (Battersea, London) are, for their scale and ambition, perhaps the most remarkable feature of the interior. They were installed in the latter half of 1889. On either side of the east window the mosaics are worked in an intricate art nouveau pattern, which must have been considered very daring at the time the church was consecrated. 

Below the mosaics are elaborately patterned tiles which include more Christian symbols. The four evangelists appear in the traditional representations:

• St Matthew as a winged man
• St Mark as a lion
• St Luke as an ox
• St John as an eagle.

Intricately worked into the tiles can be seen the symbols of Christ's passion - the cross, a cup, a bunch of hyssop, a ladder with a reed and sponge, a pillar, a scourge, a crown of thorns, a wounded heart, hands and feet, and dice. Also to be found are a six-pointed star, the lamb of God with the banner of victory, a pelican plucking her breast to feed her young, and four roundels with extracts from Te Deum, the Church's great hymn of praise. 

High on the walls of the Sanctuary to either side of the High Altar are twelve mosaic figures depicting the Twelve Apostles, each bearing an implement representing some part of their life or the manner of their death.

On the north side from left to right can be seen:

• St Matthias (who was chosen to take the place of Judas Iscariot), who carries a lance with which it is said he was put to death
• St Simon the companion of Jude carries a saw, because he was killed by being sawn in half
• St Thomas, the patron saint of builders, carries a builder's square
• St James the Less carries a fuller's bat, with which he was beaten to death
• St Matthew has a purse to indicate that he was a tax gatherer
• St Jude is seen with a sword.

On the opposite side also looking from left to right can be seen

• St Peter with the keys of the Kingdom
• St Andrew with a cross on which he was crucified
• St James the Great with a pilgrim staff
• St John with a poisoned chalice
• St Philip who was stoned to death
• St Bartholomew with a flaying knife which was used to execute him.

All these figures are to the design of Charles William Mitchell.