The servant motif in Scripture traces God's pattern of advancing his purposes through chosen agents who bear his mission in obedience and suffering, finding its fullest expression in the Suffering Servant of Isaiah, who is Jesus Christ.
The servant motif is one of Scripture's most surprising and persistent patterns. God does not accomplish his purposes through the powerful, the self-sufficient, or the triumphant. He works through servants: those who are called, commissioned, and often called to suffer in the course of their mission. In the OT the servant is both an individual title (Moses, David, Isaiah, the prophets) and a corporate one (Israel as God's servant among the nations).
The Servant Songs of Isaiah (Isaiah 42, 49, 50, 52-53) present a singular figure who will accomplish what Israel as a nation failed to do: bear the nations' sin, restore the exiles, be a light to the Gentiles. In the NT Jesus explicitly identifies himself with this figure. He came not to be served but to serve, and to give his life as a ransom for many (Mark 10:45).
Paul takes the servant pattern and applies it to apostolic ministry: those who proclaim Christ do so as clay jars, weak and expendable, so that the surpassing power belongs to God. The whole church is called into a servant vocation that mirrors the pattern of its Lord.