I wonder if it permissible to join a political party here in the west, I live in Ireland and interesting in joining the main political party here (the republican party) whereas I do believe can lobby some issues concerning Muslims in this country in the future.

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. We ask Allaah to exalt his mention as well as that of his family and all his companions.

In principle, it is not permissible for a Muslim to join a party which is founded on principles that contradict Islam, like secularism, nationalism and so forth. This is because it is a form of taking the enemies of Allaah as allies and helping them in their falsehood. Allaah Says (what means): {O you who have believed, do not take My enemies and your enemies as allies, extending to them affection while they have disbelieved in what came to you of the truth.}[Quran 60:1].  Allaah further Says (what means): {And cooperate in righteousness and piety, but do not cooperate in sin and aggression.}[Quran 5:2]. However, if some Muslims reside in non-Muslim countries and the Muslim community there sees that there are some religious benefits which can be achieved for the Muslims, like getting benefits and repelling harms by participating (in a given form of participation) in a given party, like voting in elections or nominating Muslim members in the election, then there is no harm. That is because the group could be supporting the individual and protecting him from afflictions. Nonetheless, this decision should not be taken individually, as by doing so, one is subjecting himself to reasons of afflictions.

Allaah Knows best.