The term 'Theology' literally means the study of God, deriving from the Greek word theos, meaning 'God', and the suffix -ology from the Greek word logos meaning "the character of one who speaks or treats of [a certain subject]", or simply "the study of a certain subject". It now means the science of God or of religion, typically as it is practised in a systematic and reasoned or philosophical manner. Saint Augustine defined theology as 'reasoning or discussion concerning the Deity'.

Theologians use various forms of analysis and argument (philosophical, ethnographic, historical, spiritual and others) to help understand, explain, test, critique, defend or promote any of myriad religious topics, discussing such issues by applying reason and perception to dogma (divine or ecclesistical authority). It might be undertaken to help the theologian:

• understand more truly his or her own religious tradition,
• understand more truly another religious tradition,
• make comparisons between religious traditions,
• defend or justify a religious tradition,
• facilitate reform of a particular tradition,
• assist in the propagation of a religious tradition, or
• draw on the resources of a tradition to address some present situation or need,

among other things.