Cannot an atheist, Jew or Muslim fight for liberation?

In over 30 years of walking with Christ I've heard many definitions of what a Christian is: one in a personal relationship with Jesus, one who's been baptised in water, one who's a member of a church, one whose recieved the baptism of the Holy Spirit etc. To me it's pretty clear that it's one who believes what has been called out in the Nicean Creed, which I believe should lead one to do all of the above, including fighting for liberation. Defining the faith by a political idea, however, gets it in the wrong order. If we identify with Christianity because the religion makes a good argument for liberation it's easy to forget Christ. If instead we put our faith in Christ, who brings us to liberation, Christ can continually direct our entire life.