According to the inscription over the main portico, the church dates from 1846,[1] the year António de Freitas (an ex-seminarian born in Fajãzinha, returned from Macau, where he had made his fortune in the traffic of opium and child slavery.

[1] In his gratitude to God for saving his fortune ("as a sign of his recognition for the safety of all his possessions"), he decided to finance the construction of a new church, to the invocation of the Holy Trinity, in Mosteiro.

[1] The single-nave church longitudinally extends to the presbytery, which is narrower, and addorsed by lateral bell tower and sacristy, plastered and painted while, while covered in ceiling tile.

[1][2] In the centre is the rectangular, framed doorway surmounted by frieze and cornices, topped by an inscription and a large circular oculus flanked by stone sculptures in the form of candles.

[1][2] The tower is decorated with a bulbous cupola and pinnacles on each corner, while it is accessed from the rear through a door located at the level of the choir loft, preceded by an exterior staircase, constructed over washrooms.