The reconciliation between the Churches of the West and the East explains the rapprochement of the Church of Ravenna to the Pope.
Archbishop Maurus (648-71), followed by his successor Reparatus (671-77), had proclaimed himself autocephalous, refusing to be recognized and consecrated, according to ancient custom, by the Pope; but the new archbishop Theodore came in person to Rome to regularize his position and pay homage to AGATHO (Easter 68). He also intervened resolutely in a matter concerning the distant Church of England. Theodore of Canterbury had subdivided the diocese of York into four others. The incumbent of that See, Wilfrid, reduced to the see of Lindisfarne, protested. Theodore then deprived him even of that see. Wilfrid came to Rome, where envoys of Theodore also arrived. AGATHO entrusted the resolution of the matter to the Roman synod (Oct. 679), which decided to restore the see of Lindisfarne to Wilfrid, to whom the right to appoint the other bishops was also recognized.
The most important affairs of the brief pontificate of AGATHO were the condemnation of Monothelitism and the reconciliation with the Eastern Church. Constantine IV Pogonatus had written to Pope Donus (12 Aug. 678); but since he had already died (11 Apr. 678), the imperial letter was received by AGATHO. In a matter of such importance, he wished to hear the opinion of the entire Western Church and therefore called for the convocation of local synods. Having received their responses, AGATHO convened a council in Rome for Easter, attended by 125 bishops. There a profession of faith on the doctrine of the two wills in Christ was drawn up, and delegates of the Pope and the council were chosen for the conference to be held in Constantinople. This convened on 7 Nov. 680 in the hall of the imperial palace called the Trullo (cupola); and it constituted the Sixth Ecumenical Council (Constantinople III, 7 Nov. 680–17 Sept. 681). It condemned Monothelitism and its partisans; instead, it accepted “faithfully with open arms” the doctrine of the two wills in Christ, as set forth in AGATHO’s letter. Moreover, in the address to the emperor it declared: “A confession written by the finger of God was given to us from ancient Rome; the splendid light of faith shone upon us from the West. Here we see a written page; but it is Peter who has spoken through the mouth of AGATHO.” On that occasion the emperor abolished the tax demanded by the court for papal confirmation; but not the confirmation itself, which ceased with Benedict II (684-85). Indeed, the latest formula preserved for us in the Liber Diurnus for requesting imperial confirmation is not later than 680. At his death, AGATHO was buried in St Peter’s. The text of the epitaph that extols the deceased has been preserved for us (G. B. de Rossi, Inscriptiones christianae urbis Romae, II, 52, 129, 157). He is venerated as a saint by the Roman Church on 10 Jan. and by the Greek Church on 10 or 20 Feb.