By the age of 13, he was enrolled at the Colégio dos Órfãos in Porto, where he distinguished himself in Latin and rhetoric, capturing the attention of the Augustinian monks.
At the age of 25, João entered the Order of Discalced Augustinians at the Convento de Nossa Senhora da Piedade in Santarém.
[2][3][4] Frei João de Sahagún's dedication to religious life and scholarly pursuits made him a respected member of his order, and his desire to serve in missionary work grew stronger over time.
[1][2][3][4] Upon his appointment, he worked to address the severe divisions within the local clergy and clergy-related disputes that plagued the island's religious community.
[4] Upon his return, the island of São Tomé faced frequent attacks from French forces leading to the destruction of the Church of Nossa Senhora da Conceição, adjacent to the convent of the Augustinian Order.