Is it a good idea for Christians to get involved in politics, because if they are involved in it, they tend to lie, make promises they can't fulfill and sometimes get their hands dirty which is sin.
And ministers of the Gospel, are they suppose to endorse any candidate to their congregants. What's your take?
That is rather a matter of personal choice and how each one of us sees their religion and also depends on the church ones attends.
For example, Catholics and Christians (in general) do not see anything from by participating within the world of politics, because to them, it is rather a way to try to improve the world and fighting sin and evil. Which is rather a very optimistic approach on how politics works. Though, because of their system of believes, it is common to see people of faith missing their personal religious views with the state.
In the other hand, there are sects of Christianity which discourage people from participating in politics, because in the eyes of theor church, the wordly things are already are already predefined and controlled by their settings on the books of revelations. The Jehova Witnesses are a good example, they do not participate much beyond voting, they pray and wait for the second coming of Jesus, since the world is to be cleaned from all evil since that coming day.