Excerpt from Concordant Watch:
"In order to get this symbolic church-state connection codified in a concordat, serious negotiations had already been begun in 1937. It was time for Salazar to confirm his role of protector of the Catholic Church which, of course, in turn protected his own rule. Yet, despite the good relations between Salazar and the Church
negotiations on the Concordat were long and complex. One of the sticking points was the ACP (Portuguese Catholic Action) , which Salazar was adamant should be excluded from the negotiation process. Salazar feared that ACP would be transformed into an instrument of Catholic political activity if the church were to insist on its inclusion, seek to guarantee its legal recognition or ensure conditions that would be favourable to its activities. [...] The negotiations on the Concordat also generated polemics on matters such as the prohibition of divorce to Catholics and the consecration of religious education in public schools. On these matters, Salazar was prudent: he feared the reaction by the regime's republican supporters and initially resisted Rome's demands. In the end, however, he consented. 
In 1940 these negotiations led to the signing of two concordats: one for mainland Portugal and a missionary accord for its colonies. The latter were called “overseas provinces” in order to evade the issue of decolonisation: no colonies, no problem.  Domestically, as well, Portugal remained an anachronism, with Portuguese society the most conservative in Europe. For instance, until after the death of Salazar in 1968 married women couldn't even get a passport or leave Portugal without their husbands' consent.  Salazar's regime outlived him by several years, but finally in 1974 it was ousted in the Carnation Revolution. The new Constitution of 1976 changed the repressive legal system, as did the implementation the same year of a Protocol to the concordat which finally permitted civil divorce for Catholics."