Christ was not widely known among the people—most would not
recognize Him—and He would travel from village to village and from wilderness
to wilderness; and so it was that when they set out to arrest Him they knew not
where to find Him or how to recognize Him. Judas Iscariot came to them and said: “I will show Him to you.” They
said: “When we enter that place, how will we know who is Christ?”  Judas said: “The one whom I will kiss is Christ.” 
- ‘Abdu’l-Baha  (From a talk, included
in ‘Additional Tablets, Extracts and Talks’, prepared by the Baha’i World
Center; Online Baha’i Reference Library of the Baha’i World Center)