theology: (noun) the study of the nature of God and religious belief.
• religious beliefs and theory when systematically developed: in Christian theology, God comes to be conceived as Father, Son and Holy Spirit
ORIGIN late Middle English (originally applying only to Christianity): from French théologie, from Latin theologia, from Greek, from theos ‘god’ + -logia (see -logy)
Theology is a misnomer, or a misleading word in some way. Reading the definition above, one could get the idea that everything that there is to know about God, the sum total of belief about him and everything that people do that is to do with God has been 'systematically developed' in the same way that computers have been developed or a modern education system is developed: in other words, human beings started off with nothing and, through careful, methodical work, established something. Or in this case Someone.
As a believer knows, it's actually the other way round. In Heaven, the angels probably study something called 'humanology', defined as the systematic development of beliefs and theories about humankind. But we will have to work with the definition of 'theology' above. It's the only one we have.
This page is about anything to do with 'theology' or beliefs and theories about God.
You can also browse for books on theology here.