All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
One should not socialize with or befriend bad company because they cause harm to the person in his religion, and the Prophet said: “Do not befriend except a believer and do not share your food except with a pious person.” [At-Tirmithi] The Prophet also said: “A person follows the religion of his friend; so each one should watch whom he befriends.” [Ahmad and Abu Daawood]
There is no doubt that a person who abandons the prayer and insists on committing Zina (fornication or adultery) is an evil man whom one should avoid and refrain from socializing, unless one intends to advise him and guide him.
For more benefit on advising a person who abandons the prayer and deserting him if he does not take heed, please refer to Fataawa 84390, 9384 and 85074.
Allaah Knows best.