Question: When did the city where the creator of The Perugia Altarpiece died officially become a Christian country?

<P0-S0> libya (; ; ), officially the state of libya, is a country in the maghreb region in north africa, bordered by the mediterranean sea to the north, egypt to the east, sudan to the southeast, chad to the south, niger to the southwest, algeria to the west, and tunisia to the northwest. <P0-S1> the sovereign state is made of three historical regions: tripolitania, fezzan and cyrenaica. <P0-S2> with an area of almost , libya is the fourth largest country in africa, and is the 16th largest country in the world. <P0-S3> libya has the 10th-largest proven oil reserves of any country in the world. <P0-S4> the largest city and capital, tripoli, is located in western libya and contains over one million of libya's six million people. <P0-S5> the second-largest city is benghazi, which is located in eastern libya. <SEP> <P1-S0> Nicene Christianity became the state church of the Roman Empire with the Edict of Thessalonica in 380 AD, when Emperor Theodosius I made it the Empire's sole authorized religion. <P1-S1> The Eastern Orthodox Church, Oriental Orthodoxy, and the Catholic Church each claim to be the historical continuation of this church in its original form, but do not identify with it in the caesaropapist form that it took later. <P1-S2> Unlike Constantine I, who with the Edict of Milan of 313 AD had established tolerance for Christianity without placing it above other religions and whose involvement in matters of the Christian faith extended to convoking councils of bishops who were to determine doctrine and to presiding at their meetings, but not to determining doctrine himself, Theodosius established a single Christian doctrine (specified as that professed by Pope Damasus I of Rome and Pope Peter II of Alexandria) as the Empire's official religion. <SEP> <P2-S0> In 1445 Pope Eugene IV summoned him to Rome to paint the frescoes of the Chapel of the Holy Sacrament at St Peter's, later demolished by Pope Paul III. <P2-S1> Vasari claims that at this time Fra Angelico was offered the Archbishopric of Florence by Pope Nicholas V, and that he refused it, recommending another friar for the position. <P2-S2> The story seems possible and even likely. <P2-S3> However, if Vasari's date is correct, then the pope must have been Eugene IV and not Nicholas, who was elected Pope only on 6 March 1447. <P2-S4> Moreover, the archbishop in 1446–1459 was the Dominican Antoninus of Florence (Antonio Pierozzi), canonized by Pope Adrian VI in 1523. <P2-S5> In 1447 Fra Angelico was in Orvieto with his pupil, Benozzo Gozzoli, executing works for the Cathedral. <P2-S6> Among his other pupils were Zanobi Strozzi. <SEP> <P3-S0> the so-called tiberina republic (italian: "repubblica tiberina") was a revolutionary municipality proclaimed on 4 february 1798, when republicans took power in the city of perugia. <P3-S1> it was an occupation zone that took its name from the river tiber. <P3-S2> a month later, the government of all the papal states was changed into a republic: the roman republic, which perugia belonged to. <P3-S3> its head was a consul and it used a tricolor similar to the french flag. <SEP> <P4-S0> The Perugia Altarpiece (Italian: "Pala di Perugia") is a painting by the Italian early Renaissance painter Fra Angelico, housed in the Galleria Nazionale dell'Umbria of Perugia, Italy.