This study examined Christianity and political leadership in Nigeria: A perspective from St. Thomas Aquinas' political philosophy. The aim of this article is to examine Christian's involvement in political leadership in Nigeria. The study adopted the social-historical approach which combines social and historical facts. The researcher discovered that the church interacts regularly with politics or politicians and government. However, the study ascertained whether or not a true Christian should participate in politics. Thus, this study discussed Christianity; how can Christian Politicians be effective; relationship between Christianity and politics; and the implications on political system as related to St. Thomas Aquinas' and political philosophy. The study concluded that, since political leadership is instituted by God, it cannot be said to be dirty and something to be avoided by faithful Christians. The researcher however recommends that, the Church should encourage all Christian–politicians to see the need to participate in political governance in the society and Christian–politicians should remain patriotic to deliver democratic governance, and also that the Christian Association of Nigeria (CAN) should organize conferences and seminars in order to sensitize church leaders on the need to encourage members to participate in politics.