Should the church ever become involved in politics?
If you mean should the Church endorse a particular candidate running for election or choose a political party, my firm answer would be NO! Political governments and churches serve two completely different roles. The functions of both are important; ideally, the church would support the government and vice versa. But, unfortunately, sin forbids that from happening.
The church as a whole needs to stand up for the Word of God and defend its principles at all costs. The body of Christ, individually, needs to take those principles to the polls. Votes should be cast not necessarily along party lines, but rather along the dividing line of a candidate's principal beliefs. But, when the Church gets involved in campaigning for a certain candidate or party, it can only cause disaster and division.