Monergism

Systematic theology is any study that answers the question, "What does the whole Bible teach us today?" about any given topic.
Wayne Grudem (Systematic Theology, pg. 13)

We need theology for the sake of people. Theology is the application of the Word by persons to the world and all areas of human life.
John Frame (Salvation Belongs to the Lord, pg. 72)

Theology...the church's reflection on God's performative action in word and deed and its own participation in the drama of redemption.
Michael Horton (Covenant and Eschatology, pg. 4)

Theology is the intellectual, relational and spiritual act of knowing God through the disciplined and communal practice of understanding and applying His word to all areas of life.
A. Orendorff

Every Christian should be a theologian.
John Blanchard