The Greek word marturia means testimony or witness — the formal declaration of what one has seen or knows to be true. In legal contexts it denotes court testimony; in theological contexts it describes the witness borne to Christ, to God's truth, and ultimately by martyrs with their lives.
The marturia concept is foundational to Johannine theology. The Gospel of John opens with the Baptist's witness (marturia) to the Light, and the entire Gospel is framed around testimony: the Father testifies to the Son, the Spirit testifies, the disciples testify. 1 John 5:9-11 presents a cascade of divine testimony culminating in the declaration that God has given us eternal life in His Son. The very word 'martyr' comes from this root — those who bore ultimate witness with their blood. Revelation 12:11 declares that the overcomers conquered the dragon 'by the blood of the Lamb and by the word of their testimony (marturia).' Witness to Christ is inseparable from Christian identity.