We thank Allah (Exalted be He) that He has guided you and we implore Him to make you steadfast and consistently observant of Islam - indeed He is All Hearer and All Responsive. It is obligatory for you to be dutiful to your parents and treat them kindly and you should avoid speaking harshly to them. You must try your best to fulfill their needs. However, it is not permissible for you to obey the order of your father to shave off your beard because the Prophet (peace be upon him) said:
"Trim closely the moustache, and let the beard grow."
(Agreed upon by Al-Bukhari and Muslim) The Prophet (peace be upon him) also said:
"It is obligatory for a Muslim to listen and obey (the appointed authority) whether they like it or not, except when they are ordered to do a sinful thing; in such a case, there is no obligation to listen or to obey."
(Agreed upon by Al-Bukhari and Muslim). Your father fears that people may talk ill of you or despise you due to your adherence to Islam and sitting with righteous people, but you may tolerate this fact by telling him that Allah (Exalted be He) has made Islam a test for people so that the one who adheres patiently to it will gain the pleasure of Allah (Exalted be He) and enter His Jannah (Paradise). People hurt Prophet Muhammad (peace be upon him) who is the premier of people and most loved person to Allah (Exalted be He). They depicted him as a mad man and a sorcerer, put the abdominal contents of a slaughtered she-camel between his shoulders, cast stones at him, and severely beat and tortured his Sahabah (Companions of the Prophet) until some of them died. Nonetheless, they patiently adhered to Islam and as a result a new person used to embrace Islam every day until the Muslims became stronger and glorious as Islam prevailed. Similarly, these days Islam has become strange and Multazim persons are pursued and displaced and false accusations are made against them. However, Allah (Exalted be He) will make Islam reign supreme by their persistent adherence to it and patience in spite of the harm, insults, and mockery they experience. (Part No. 2; Page No. 329) Many Muslims at all levels have started practicing Islam and are returning to it every day. Allah (Exalted be He) says:
So be patient. Surely, the (good) end is for Al-Muttaqûn (the pious)
He (Exalted be He) also says:
O you who believe! Endure and be more patient (than your enemy), and guard your territory by stationing army units permanently at the places from where the enemy can attack you, and fear Allâh, so that you may be successful.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.