Is it Islamically forbidden to boycott a friend who holds anti-religious views and whose influence you fear?

Striving to guide a friend and protect him from misconceptions is religiously desirable. One should seek help from specialists or lend him beneficial books and tapes if one's own scientific capacity is insufficient. If you fear being influenced by his deviant ideas, then beware of sitting with him, for "a person is upon the religion of his intimate friend," and a bad companion can have a negative influence.