Mor Osthatheos Sleeba, the saintly Syrian father venerated with great affection by the Malankara Syrian Christians, was born on January 1 1854, in the village of 'Kfarzo' in Mesopotamia situated in the south-east Turkey.  He belonged to the 'Abakker' family, his father was Salbi and mother Nabuna.  His baptismal name was 'SALIBA' (Sleebo/Sleeba). When he was only three years of age his father, Salbi, passed away.  A few years later his two brothers and two sisters also died of a deadly disease.  Only Sleeba (Saliba), his mother and one sister were fortunate to survive from the epidemic.

At the age of seven Sleeba started his education under his uncle Kassisso Danaha.  Later his studies continued under Raban Shem`un at the Damascus church. From the childhood days itself he was very conscious in regular Prayers, lent & meditation. The Church's liturgical hymns and its rich traditions was of great inspiration for the young Sleeba. By the time he completed his education, he mastered in Syriac, the liturgical language of the Holy Church. 

Even while continuing his studies he worked in nearby villages for his livelihood.  In 1880, he was ordained Koroyoo (Deacon) by his Malphono (Malpan/teacher) who by then had been elevated as Metropolitan for the Damascus diocese by name Mor Athanasius Shem`un. (H.G. is the patriarchal delegate who is entombed at Kottayam Puthenpally).

Deacon Sleebo, who was then 27, accompanied the newly appointed Patriarchal delegate, H.G. Shem`un Mor Athanasius to Malankara and reached Cochin on January 1, 1881.  They stayed in a small room at Kottayam Puthenpally and preached the Holy Gospel of Our Lord, both within our Church and outside.   During this period, the nearby Kottayam St.Mary's Cheriapally and Syrian Seminary (old Seminary at Kottayam) were under the control of the European missionary activists.  In 1889, when the Old Seminary was returned to the Jacobite Syrian Church following a court verdict,  Shem`un Mor Athanasius and Deacon Sleeba were requested to reside at seminary and teach theology and Church traditions to the seminary students.

On June 11 1889, the Patriarchal delegate Mor Athanasius Shem`un passed away at a most unexpected time.  The sudden demise of the Metropolitan was a severe blow for our Deacon Sleeba.  He is said to have remained alone for many days, crying and crying.  He may have felt lonely in a land far away from his native place.  Subsequently our Lord gave him strength to overcome the difficult times; after a short interval, he continued to preach the Holy Gospel, travelling throughout Malankara.   His speeches were in Syriac and the main translators were Deacon Mathew (later Catholicos Augen I), Deacon M.J.Michael of Kayamkulam (later Michael Mor Dionysius of Kottayam & southern dioceses) and  Kassisso P.P. Joseph (father of late Catholicos Baselios Paulose II).  The annual conventions held during those times in Aluva Manalpuram (river side), were very famous with his speeches and attracted many to our Holy Church.   He used to stay at the convention site for the entire period without much food, thus saving the money and kind he received and donated it to the needy.  His dedication made him so popular; the poor considered him as great prophet and as a friend in need.  (The annual conventions held at Aluva Manalpuram were the first of its kind, anywhere in Malankara. The famous Maramon Convention started only a few years later).

After the demise of Mor Athanasius Shem`un, Deacon Sleeba came closer with Mor Gregorios Geevarghese (Parumala Thirumeni).  Syriac was the medium that is believed to have brought both of them together. St. Anthony of Egypt, the Coptic monk who lived in the 3rd century was of a great inspiration for both. Their intimate relationship continued until the last of Kochu thirumeni.

When a group from Malankara under the leadership of Parumala thirumeni set forth for a pilgrimage to the holy city in 1895, Deacon Sleeba was also asked to accompany them as a guide. The other prominent members of the group were Kochuparambil Paulose Ramban (later Paulose Mor Kurillos - Panampady Church, the Malankara Metropolitan, 1911-1917) and  Wattasseril Fr. Geevarghese (Malankara Metropolitan, 1909).   St Gregorious in his famous travelogue "Oorsalem Yatra Vivaranam", has mentioned about Deacon Sleeba's help during many occasions and also about their stay at the 'Sehion Malika'/Dayaro of Markose at Jerusalem.  The passing away of Parumala Thirumeni on Nov 2, 1902 was another of the saddest moments in the life of Dn.Sleeba after the demise of his Malphono Mor Athanasius Shem`un.   He was at Parumala during the last ceremonies of the late Metropolitan and remained there for many more days.

Dn. Sleeba, though only six years younger than Parumala Thirumeni, remained as a deacon until he reached 52 in 1906.  During these days his emphasize was on the preaching of Holy Gospel among the mass and guided the theological students.  The ordination of Dn. Sleeba as the Metropolitan was at the age of 54, six years after the demise of Parumala Thirumeni.

In 1906 a Patriarchal bull reached Malankara, requesting Dn. Sleeba to reach the Dayro at Mosul (Iraq) for his ordination as Metropolitan.  Before his departure to Mosul, a grand public reception was given to Dn. Sleeba by Malankara Metropolitan H.E. Mor Dionysius Joseph and was presented with a gold chain and Holy Cross as a gift of the Malankara Church.  He together with Deacon Mathai of Cheettalathumkara (later Catholicos Mor Augen I) left for Mosul the same year. Thus after 25 years in Malankara as a deacon, in 1906 Deacon Sleeba was ordained as Kassisso (Full Priest) at the age of 52 and two weeks later as 'RABAN' (Monk Priest/Ramban) by Mor Kurillos Elias Qudsho, at the Monastery of Mor Mattay, near Mosul.  The Priestly consecration ceremony of Deacon Mathai was also held on the same occasion.

Later Raban Sleeba and Kassisso Mathai went to 'Kurkkuma Dayro' (Deir'ul Zaffaran Monastery in Turkey) and stayed with the new Patriarch Mor Ignatius Abded' Aloho (Abdullah II) for a few days.  From there they went to the house of our Raban Sleeba at the 'Kaferzo' village in Tur'Abdin (Present Turkey).  Raban Sleeba's only sister was living there.  For the next two years, Raban Sleeba together with Deacon Mathai visited many of the nearby Syriac Orthodox churches and preached the Holy Gospel.  (Deacon Mathai became well versed in Syriac during his long stay with his close friend Raban Sleeba.  Patriarch H H Ignatius Elias III ordained him Metropolitan in 1927 by name Thimotheos and in 1964 Patriarch H H Ignatius Yakoob III elevated him as the first canonical Catholicos of India by name Augen I).

In March 1908 Patriarch of Antioch & all the East Moran Mor Ignatius Abded' Aloho (Abdullah II) consecrated Raban Sleebo as Metropolitan and was entrusted with the name OSTHATHEOS. The ordination ceremony was held at the church of the 'Forty Martyrs' in Mosul and appointed him as the Apostolic Delegate of the Holy See to India, succeeding his mentor Mor Athanasius Shem`un.  

On 31st May the same year, Kochuparambil Paulose Raban (Mor Kurillos) and  Wattasseril Geevarghese Malpan (Mor Dionysius) were also ordained as Metropolitans at the St.Mark's Dayro in Jerusalem by Patriarch Mor Ignatius Abded' Aloho (Abdulla II).  RABAN ordination of Deacon Mathai (later Mor Augen Thimotheos) was also on that auspices occasion. (Wattasseril Mor Dionysius become the Malankara Metropolitan in 1909 following the demise of Pulikottil Joseph Mor Dionysius in the previous year.  Two years later, the Saintly Kochuparambil Paulose Mor Kurillos was elevated to the highest order of Malankara Metropolitan.)

After the Metropolitan consecration, Mor Osthatheos Sleebo, along with the other two newly ordained bishops and Ramban Augen, returned to India and assumed the responsibility of the Patriarchal representative in Malankara.  When the Malankara Metropolitan Mor Dionysius Joseph passed away in 1908, Mor Osthatheos Sleebo was given charge of the Malankara church administration temporarily.  In 1909 the Apostolic Bull appointing Wattasseril Mor Dionysius as Malankara Metropolitan was issued by the Patriarch Mor Ignatius Abdulla II.  Unfortunately, a major split occurred in the Malankara Syrian community just two years later in 1911; Wattasseril Mor Dionysius emerged as the leader of the dissident group.  It was actually the disputes between Wattasseril Thirumeni and his co-trustees, Corepiscopus Mathen Malpan Konattu (Priest trustee) and  Mr. C.J. Kurien Akkara (lay trustee), that led to the sad split. The conflict intensified with the co-trustees openly demanding for more transparency in financial matters which the Metropolitan trustee Mor Dionysius Wattasseril could not accept at all.  When complaints against the Methran reached the visiting Patriarch Moran Mor Ignatius Abdulla II, His Holiness asked for explanation; this prompted the agitated Wattasseril Methran to revolt against the supreme pontiff.  Since then a group called "Methran's party" started functioning in Malankara under the leadership of Wattasseril Mar Dionysius Methran and his colleagues.

These disputes made the responsibility of Mor Osthatheos Bava even more greater; he along with the newly elected Malankara Metropolitan Paulose Mor Kurillos (Panampady) and Paulose Mor Athanasius (Valiya Thirumeni) worked tirelessly to retain the true apostolic faith of the Syrian Church.

On 19th  March 1930 at the age of 76, Mor Osthatheos Bava passed away and his mortal remains were interred at the Arthat St.Mary's Simhasana church, Kunnamkulam.  This church is now a major pilgrim centre of the Malankara Syrian Christians.  Because of the tomb of the saintly father, the church came to be popularly known as 'Bava Pally' (the church of Mor Osthatheos Bava).
 

In 2000, the visiting Patriarch of Antioch & all the East, through bull dated 4th April, officially proclaimed Mor Osthatheos Sleebo and Mor Gregorios`Abdul Galeel as Saintly Holy Fathers, thereby permitting to recite the 'Quqalya' hymns and prayers of the 'Zadeeqo' (saints) at their tombs and  beseech their intercession (see Patriarchal Encyclical dated April 9th, 2000). In 2005, the historical patriarchal bull allowing the local Simhasana church to recite the name of St. Osthatheos Sleeba in the fifth 'Tubden' (diptych) was issued and later through the Apostolic bull dated 26th September 2008, the name of our holy father was permitted to be recited in all the Malankara churches.