Thomas the Twin, Doubting Thomas

"Thomas the Twin" is redundant because Thomas means Twin and was a  nickname.  The proper name of Thomas the Apostle was Judas bar Alphaeus, or Judas son of Alphaeus. The word "Thomas" was never used as a proper name 2,000 years ago, but was usually used as a nickname to describe the younger of a pair of twins.  

This novel includes the story of the older twin of the pair, who probably died in his teens. If the older twin had died before his teens, Thomas would have shed the nickname of Thomas and would have been addressed as Judas.  

Both James and Matthew (Levi) are mentioned in the Gospels as being the sons of Alphaeus. These two are often listed with the name Thomas between them, as in: "Matthew, Thomas, James son of Alphaeus" which was probably originally given as "Matthew, Thomas, James, sons of Alphaeus". Since Matthew and James were very different from Thomas, neither could have been his twin, although they certainly remembered his twin. 

  Doubting Thomas was a label given to Thomas because he doubted that Jesus had risen, which is true. He only believed after he placed his hands on the physical risen Jesus. This was also true of all of the other disciples, which you see if you read the Biblical accounts carefully. 

Thomas, however, was the first to openly declare, "My Lord and my God."

Unlike the others, Thomas set out a week after the Pentecost to set into action his faith and his belief. He followed Habban to travel to the land of Gondaphorus in Parthia because his Lord asked Thomas to do this.

The impact of Thomas the Apostle was so strong that within one hundred years of his death, some children were formally named Thomas, which ceased to be a nickname for Twin.