There are no authentic documents to prove the establishment of this Pilgrim Centre. However evidences are there to prove that this church has existed during the period when Sakthan Thampuran (1775-1790) reigned over the erstwhile Cochin Province. It is believed that the church which is an epitome of an ancient era, dating back to the 14th Century, was established on September 8, 1381
The church has many popular beliefs woven around it. Six centuries back Kerala was divided into numerous provinces ruled by kings and landlords. Two of such neighbouring landlords were Koratty Kaimal and Kodassery Kartha. The descendents of these two feudal lords live in Koratty even now, and this adds on to the authenticity of this belief about the origin of the Koratty Church. Under the feudal lord, Koratty Kaimal, many Christians served in the army. In a battle between Kaimal and Kartha many were killed. Sri Kavalakkadan Kochu Vareed, the commander of the Kaimal army was one among the dead. At the time the Catholics had only one church in that area - at Ambazhakkad. Kaimal made all arrangements for the funeral of Sri. Kochu Vareed to be held in full military honours and religious rituals at the Ambazhakkad church. But his rival, Kodassery Kartha interfered and the burial could not take place there. The funeral procession had to return. In between, the pall-bearers had to rest and they placed the coffin down. When they tried to lift the coffin again they found to their astonishment, that it was firmly stuck to the ground and they could not lift. Knowing this, Koratty Kaimal made all arrangements for the burial there itself and gave instruction to build a church for the welfare of his Christian subjects. Today at that spot stands a granite stone cross. Kaimal gave away lots of land, free from tax, to sustain the rituals in the church. This church gradually was known as the Marian Pilgrim Centre of Koratty Muthy.
Another strong popular belief is that connected with offering of Poovankula. Years back a devotee of Koratty Muthy hailing from Meloor, another hamlet 10 km away from Koratty was bringing a bunch of a special variety of plantain (locally called "Poovan pazham") to be offered to Koratty Muthy. Enroute when the devotee reached Muringoor, a rich farmer who was getting some work done through the labourers in his farm asked the devotee to give two plantains from the bunch. The devotee refused as the entire bunch was an offering to Koratty Muthy. The rich man got irritated and forcibly plucked two plantains from the bunch and ate it. He developed a pain in his stomach and started wreathing. The stomach ache continued unabated in spite of so many treatments. The physicians told him that there was no apparent sign of any disease as such and the only remedy could be to repent the misdeed and make reparation. And the rich man gave away half of the land in which he had put his labourers to work as an offering to Koratty Muthy. No sooner had he done this, the stomach ache vanished.
The pictures of 12 apostles are embossed on a wooden frame
Important events relating to the life of Mother Mary are painted on the walls inside the church
Built on the lines of ancient Kerala Sculpture.(During the feast days the original statue of Koratty Muthyis taken in procession from the church and placed forveneration in Roopa-pura).