Answer
(Fatwa: 258=251/D)
This practise is not correct. Hazrat Eisa (Alaihis Salaam) is a prophet of Allah and we love all the prophets and messengers and Hazrat Eisa too, but propagating his love and reciting his Kalimah or writing his name on caps is against the traditions of Islam and it has no support from the Quran and Hadith. Moreover, writing the name of Hazrat Eisa specially may be a conspiracy of the Christian to propagate Christianity and to lessen the love of Prophet Muhammad (Sallallahu Alaihi Wasallam). Therefore, it must be avoided. If you can convince him politely you should do that otherwise you should at least dislike this practice.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband