What is the ruling on naturalizing in a Western country while retaining one's original citizenship, and is there definitive evidence of its prohibition, especially given the availability of freedom of religions and Islamic practices in those countries?

Nationality is a modern political term that was not known to early jurists. It signifies a political and legal bond between an individual and a specific state, entailing rights and duties, such as abiding by the state's laws and defending it. The original ruling on acquiring the nationality of disbelieving states is prohibition, due to the implications of submitting to man-made laws that contradict Islamic law, and defending a disbelieving state even if the combatant is a Muslim, which falls under prohibited loyalty (al-muwalat al-muharramah).