Rubuta ci gaba ga wannan sakin layi - An nada Barrientos a matsayin Mai bincike a wannan lokacin, kuma a cikin 1438 an zabe shi Bishop na Segovia. A ranar 3 ga Mayu 1440 an gudanar da taron cocin a cikin Cocin San Miguel na Turégano, inda ya gabatar da umarnin majalisa don ilimin tauhidi da koyarwar fastocinsa. Kasancewa da aminci ga John II, a cikin 1442 ya sake fasalin Diocese na Segovia, wanda ke ƙarƙashin tasirin ɗan sarki Henry mai tawaye, don bauta wa lardin Ávila don tallafawa Sarki. Daga baya, ya tsara sasantawa a yankin Tordesillas don ƙirƙirar gaba ɗaya don fuskantar adawa da Masarautun Navarre da Aragon. A cikin 1444 ya mamaye Diocese na Cuenca kuma a shekara mai zuwa ya ba da taimakon diocese ga sojojin yankin a Yaƙin farko na Olmedo
Ka yi haƙuri. Hakanan, a cikin 1449, ya yi alƙawarin makamai na diocese don karewa daga sojojin don Alonso de Aragón da sauran manyan mutanen Castilian waɗanda suka yi adawa da sarki. Ɗaya ya ba shi matsayin babban bishop na Santiago de Compostela, amma ya ƙi.