I'll provide a few citations here and you can note them:
"
We do not believe in the Anti-Christ in the sense the Christians do. Anyone who violently and determinedly sought to oppose the Manifestation could be called an 'anti-Christ', such as the Vazir in the Bab's day, Haji Mirza Aqasi." (Shoghi Effendi, Lights of Guidance [hereafter LOG] #987, pp. 366-67;
Abdu'l-Bahá broadens the definition of the antichrist to not only include
anyone who opposes the manifestation, but also anyone who goes against Their teachings and laws:
"These wars and cruelties, this bloodshed and sorrow are Antichrist." (Abdu'l-Bahá, Promulgation of Univ. Peace [hereafter PUP] 6)
"Whenever discord prevails instead of unity, whenever hatred and antagonism take the place of love and fellowship, Antichrist reigns instead of Christ." (Abdu'l-Bahá, PUP 6)
Notes on the Christian "Antichrist" and Titles of Christ