Five years later he earned his master's degree in Systematic Theology under the guidance of José IV, GCC and with the thesis The Christian life as an extension of the incarnation.

Martins, first big role within the Catholic Church start in 1993 when he was appointed member of the educational team of the Olivais Major Seminary of Christ the King.

[5] He arrived at Cristiano Ronaldo International Airport on February 15, 2019, where he was greeted by his predecessor before kissing the ground following the custom set by Pope John Paul II.

[9] As for the sex abuse scandal surrounding Father Anastácio Alves, Bishop Martins told the press, on his arrival to the island, that he will adopt the own way of proceeding of the Portuguese Episcopal Conference, in force since 2012.

In his first homily he appealed to the "holiness" of the priests, called for a Church that "dares to be" and does not just "appears to be",[14] asked his Diocesan Curia to give testimonial of the Risen Christ[15] and ensured "a sincere collaboration with all entities of the Madeiran society, with respect for each one of them".

[37] In September 2021, the diocese, together with the parish of São Bento (Ribeira Brava) and in partnership with the Regional Government, inaugurated the Dragoeiro Alzheimer Unit.

The fund of five hundred thousand Euros[47] resulted from a cooperation agreement with the Regional Secretariat for Social Inclusion and Citizenship[48] and aimed to financially support families' “food and fixed costs, medication and consultations, housing and rent and schooling”.

[50] Miguel Albuquerque, President of the Regional Government Madeira insisted in being contact with the Nuno I, so that together they could come up with a set of procedures aimed at resuming the activities of “face-to-face religious worship”, while abiding to all the prophylactic measures of distance and containment.

Having in mind the subsequent deaths related with COVID-19, after Summer, the bishop coordinated the Diocese's regulations with those of the Regional Government of Madeira and forbade the traditional after mass gatherings, meals and celebrations that occur after the religious services.

[54][55][56][57] During his tenure as Bishop of Funchal, Nuno Brás was responsible for the catholic celebration of centenary of the death of the Emperor-King Charles I of Austria, who died in Madeira.

[60][61] In June 2024, media outlets,[62][63] speculated that Nuno Brás would soon be transferred to the Diocese of Guarda, one of Portugal's most prestigious and oldest ecclesiastical territory.

Despite de commotion, Pope Francis ended up appointing José Miguel Pereira as Bishop of Guarda, instead of transferring Nuno Brás between Dioceses.

[66] Bishop Martins, has ascertained that the role of teachers in society needs to be bigger than "raising rich [in knowledge] people, closed to themselves in this [non-believer] small horizon".

In the same letter, Bishop Martins and his peers also took the opportunity to support and condemn the "drama of child abuse by responsible members of the Church," under a commitment to "root out the causes."

[69] In this regard, Bishop Martins did not considered the case of Father Anastácio, who is missing, and who is being investigated by the Judiciary Police due to child abuse crimes.

[79] Another action carried out by Bishop Nuno Brás, in February 2020, in an attempt to raise the issue among the catholic people in Madeira, was to hold an ecumenical vigil in the Church of the college with leaders of other main Christian faiths on the island, among them Ilse Berardo.

[80] As a member of the Portuguese Episcopal Conference, Bishop Nuno Brás advocates the referendum against the decriminalization of euthanasia in Portugal and proposes to deputies in the Assembly of the Republic a stronger investment on palliative care.

[84] The Bishop of Funchal, highlighted the importance of keeping churches in Portugal open to the public, especially those that receive investment for restoration and promotion, which in his opinion should not be closed, therefore preventing tourists and worshipers from visiting them.

He argued that keeping churches open does not represent a significant cost for local authorities and stressed the importance of ensuring public access after restoration and promotional efforts.

[84] Nuno Brás has urged the Church to overcome historical fears of losing property and to recognize that civil authorities are not seeking to appropriate ecclesiastical assets but to work together for their preservation and appreciation.

[84] In 2019, Bishop Martins expressed his concern for the lack of a young population in the Autonomous Region of Madeira and a "frightening" low number of births.

He also pointed out that young people who exist at any given moment, go to the mainland to attend university and lose their roots acquired in Madeira, implying lack of economic opportunities.

"During the 2019 Madeiran regional election Bishop Martins appealed[87][88] to candidates to use the electoral campaign as a "time of civilization" and criticized "personal attacks" and "slander" among politicians.

Contrary to his predecessors, Bishop Martins requested[88] the parties and their candidates to not use catholic churchyards as places for political campaign rallies with the use of megaphones.

[89] The Bishop of Funchal is concerned that artificial intelligence could become a form of collective control, as it makes choices based on its programming, potentially leading to a "Big Brother" scenario that enslaves society.