Grubišić was the initiator and one of the founders of humanist Hrvatska akademske udruga – Čovjek nadasve (Croatian Academic Association - Man Above All).

Grubišić started Savez za građansku i etičku Hrvatsku (Alliance for Civic and Ethical Croatia).

Despite being warned against any form of active engagement in politics by the leadership of the Catholic Church,[2] Grubišić led an independent list in the 2011 parliamentary election in the 10th electoral district, eventually winning 29.000 votes (11.7%), and two seats in Sabor.

[1][3][4] In January 2012, the Archbishop Marin Barišić suspended Grubišić for founding a political party, and accepting the parliamentary term.

[2] His suspension covered exercise of confession, preaching and celebrating the Holy Mass, as well as the ban on wearing the priestly garments.

Grubišić actively advocated revision, even termination, of the treaties signed between Croatia and the Holy See, which would, among other things, reduce the amount of taxpayer money annually given to the Catholic Church from the state budget.

When commenting on President Ivo Josipović, with whom he was a good friend, he stated that it would've been tragedy if he had been elected for a second term, because "he says what people want to hear, but he didn't initiate any changes to the matters in which he had jurisdiction".