why is thomas in the bible called the twin
Thomas the Apostle The name Thomas (Koine Greek: Θωμᾶς) given for the apostle in the New Testament is derived from the Aramaic or Classical Syriac: ܬܐܘܡܐ‎ Toma, equivalently from Hebrew Teom, meaning "twin". The equivalent term for twin in Greek, which is also used in the New Testament, is Δίδυμος Didymos.
Trinity Tertullian, a Latin theologian who wrote in the early 3rd century, is credited as being the first to use the Latin words "Trinity",[32] "person" and "substance"[33] to explain that the Father, Son, and Holy Spirit are "tres personae, una substantia".[34] While "personae" is often translated as "persons," the Latin word personae is better understood as referring to roles as opposed to individual centers of consciousness.