Is it permissible to initiate Salaam (the Islaamic greeting) with non-Muslims?

Question 412: Is it permissible to begin greeting a disbeliever, especially if they are of high positions such as a professor in a university?

Answer: It is not permissible to greet a disbeliever first even if they occupy high positions, because of the general prohibition mentioned in the Hadeeth such as the saying of the Prophet (peace be upon him), Do not start greeting the Jews and the Christians before they greet you… Related by Muslim... read more here.