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\section{A tale of two theisms}
Christian theology presupposes God's existence. It sets out to clarify \emph{who} God is and \emph{what} He is \emph{like}, not \emph{if} He is. Generally we can consider those holding a generalised concept of God and those with a distinctive trinitarian understanding.

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    \item[Old Testament] Names are important\index{God!Names of} in the OT. Israelites share the common name \emph{El} with other Semitic cultures. It is combined with many other words, most often into \emph{Elohim}. But next to the general names the Israelites also have the name YHWH, with an original meaning along the lines of `I am' or `I shall be there as who I am': the name is a promise of God's presence.

        Most striking in the OT is the development of \index{Monotheism}monotheism (Dt.~6:4, although originally this verse was an injunction to \index{Monolatry}monolatry, the \emph{worship} of one god). Monotheism implies \index{Universality}universality: God's love and faithfulness are not just for Israel, but extend to the whole of creation.

    \item[New Testament] The NT presupposes the OT conception of God, but adds the \index{Trinity}\qindex{Theism!Trinitarian}trinitarian understanding.\question{Is it correct to ascribe the idea of the Trinity to the whole New Testament, or are there writings that do not share this idea? Did Christ have this concept? Does even Paul have this concept unambiguously?} This does not break monotheism: there is one, true Creator God, but this Creator God is the Father, Son and Spirit together.

        In the NT, \emph{Theos} refers to both \emph{El} and \emph{Elohim}.\question{A proper discussion of the Greek names of God in the OT would involve the LXX.} \emph{Kyrios} is the typical translation of the tetragrammaton and means \emph{Lord} -- it is usually associated with Christ the Son. From a Christian point of view, the Trinity is the fulfilment of the promise of God's presence.
\end{description}

Classical theism\index{Theism!Classical} is a particular understanding of \emph{God as One} that, together with the trinitarian conception, emerged in the early church in discussion with Hellenistic culture. In the Roman empire, Christian apologists used it to clearly distinguish themselves from polytheism and e.g. emperor worship.

While there are differences with Greek theism (the idea of creation \index{Creation!Ex nihilo}\emph{ex nihilo}), Christian theism is largely compatible with it, especially considering the \index{Divine attributes}divine attributes (both trinitarian and metaphysical; there is tension between the two).

Medieval \index{Scholasticism}scholasticism formalised Greek theism. Anselm deduces the range of classical theistic attributes as great-making properties of divine being.

Aquinas sums up both the content and method of the core philosophical theism: human reason and philosophy, when properly applied, seem to be able to reason to something we call `God'. He describes the \emph{via negativa} and \emph{positiva}, different ways to get to divine attributes. The core project of Aquinas is to show that pure human reason is not enough and that special revelation is needed to arrive at things as trinitarian theism.

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(Philosophical) \index{Atheism}atheism is a modern phenomenon -- before, people only denied God's \emph{relevance} but not his \emph{existence}. Developments in \index{Science}science facilitated \qindex{Atheism!Scientific}\emph{scientific atheism} as scientific explanation replaced divine explanation. \qindex{Atheism!Humanistic}\emph{Humanistic atheism} arises from the \index{Enlightenment}Enlightenment's emphasis on the authority of reason and human autonomy. \qindex{Atheism!Apathetic}\emph{Apathetic atheism} is an atheism of indifference. \qindex{Atheism!Protest} is a passionate remonstrance against God in view of the fractured human condition.

The claim is that much of modern atheism is a reaction to a conception of God closer to classical than trinitarian theism. Aquinas and others gave importance to the concept of the omnipotent, etc. God. This idea leads to theological determinism, which provoked most protest from atheism.

Trinitarian theism, in fact, answers the complaints from atheists. Classical theism, being a natural theology, should have a limited role in Christian theology. In light of the biblical text, a number of divine attributes may need to be revisited if we give importance to trinitarian theism.

