The Seventy Apostles are those whom the Lord chose, in addition to the original Twelve Apostles, to go before Him into the cities He would visit (Luke 10:1), and lay down the groundwork and infrastructure for the Early Church.
According to the Gospel of Luke, the only gospel in which they appear (Luke 10:1–24), Jesus appointed them and sent them out in pairs to preach the Gospel. The Twelve generally remained at Christ's side, serving as witnesses to His life; but the Seventy preceded Him in every place He visited.
The Synaxis of the 70 Apostles is commemorated on January 4 and was established by the Orthodox Church to indicate the equal honour of each of the Seventy.
Besides the celebration of the Synaxis of the Holy Apostles, the Church also celebrates the memory of each of them during the course of the year. The Church in particular venerates and praises the Seventy Apostles because they taught us to honor the Trinity One in Essence and Undivided