Politics is defined as 'the art or science of government', and derives from the Greek 'polites', meaning 'citizen'. So if you are interested in being a good citizen - which every Christian should - you can be involved in politics.
It was God who institued civil authority in Genesis chapter 9, so why leave that kind of power to Satan?
In Britain in the late 18th Century a young politican called William Wilberforce (1759-1833) pondered over this very question when he became a Christian and considered leaving politics. Instead, he was persuaded by Christian friends that he could achieve more good for God by remaining in parliament, so he did. As a result, he fought tirelessly for the rest of his life for the abolition of slavery in the British Empire; first introducing a bill against it in 1791.
He eventually achieved the abolition of the Slave Trade in 1807, and only shortly before his death in 1833, did he see Slavery itself abolished.
There are many more examples of Christians who made a tremenous difference by being involved in politics and who helped create many of the freedoms we enjoy today. The vast majority of America's Founding Fathers were Christians, and even the few who were not were sympathetic to Christianity's moral values.
On the other hand, Adolf Hitler, Joseph Stalin and Mao Tse-Tung were not Christians, so consider; who would you rather live under?