It was his suggestion during the time of Mar Thoma IX to establish the Syrian seminary at Kottayam, Kerala's first educational institution.

In 1816, following the demise of Mar Dionysius II, who had not appointed a successor, Kurien was elected to succeed him as the Malankara Metropolitan by the general assembly of the Church (Malankara Palliyogam) and was ordained as bishop by Geevarghese Mar Philexenos II of the Malabar Independent Syrian Church.

Following the sudden demise of Pulikkottil Joseph Mar Dionysious I, on 24 November 1816, the British resident called a meeting of the Diwan (prime minister) of Travancore and elders of the church at Ernakulam.

Punnathra Kurien Ramban was ordained by Mar Philexenos (Kidangan) of the Malabar Independent Syrian Church on 19 October 1817.

An apologetic version of the Coonan Cross Oath in the letter of Dionysious Punnathara to the head of the Anglican Church Missionary Society from a translation of it out of the Syriac original:[2] "Mar Dionysius, Metropolitan of the Jacobite-Syrians in Malabar, subject to the authority of our Father, Mar Ignatius, Patriarch, who presides in the Apostolic See of Antioch of Syria, beloved of the Messiah.

Love from Christ and the people of all the churches to Lord Gambier and ....In the year of our Lord 1653, came our Spiritual Father, Mar Ignatius, the Patriarch, from Antioch to Malabar: but, when the Franks knew this, they brought the Holy Man to the walls of Cochin, imprisoned him in a cell and gave no small money to the King of Cochin.

But when we knew this, all the Jacobite Syrians in Malabar assembled in the Church of Mathancherry, which is in Cochin, and we swore a great oath, by the Father, Son, and Holy Ghost, that henceforth we would not adhere to the Franks, nor accept the faith of the Pope of Rome: we accordingly separated from them.

Due to this disease, Punnathara Mar Dionysious died on 17 May 1825 and was interred at Kottayam Cheriapally (St. Mary's Orthodox Church).