proselyte
The word is "proselytizing" but its original meaning had to do with forcing one's religion upon another.
Druidism
Christianity is a religion. It begins with the letter c.
Taoism
Paganism Protestant Christianity
Islam is a religion. It has not "other religion" in it. Perhaps, you are thinking of Emaan (إيمان) which is the Islamic concept of faith.
Judaism.
Haughty is another word for arrogant that begins with the letter H.
Physician is another name for a doctor of medicine. It begins with the letter P.
If you knew that your boyfriend liked another girl you really should sit and talk with him to see if he is committed to you or if you should end your relationship. Unfortunately when someone begins to like someone else during a relationship the outcome is never good.
A country begins trading with Another Country overseas.
Large is a synonym for big. It begins with the letter l.