In a discussion on science and religion [in his 2008 book The Reason for God], Keller seeks to justify his support for the dogma of theistic evolution. He writes: ‘Evolutionary science assumes that more complex life-forms evolved from less complex forms though a process of natural selection.

Many Christians believe that God brought about life this way. For example, the Catholic Church, the largest church in the world, has made official pronouncements supporting evolution as being compatible with Christian belief.’ [page 87].

By his statement: ‘the Catholic Church, the largest church in the world’, Keller is conferring on the Roman Catholic Church the accolade of being the largest Christian Church in the world. In his definition of Christianity, Keller is clear that he includes all Orthodox, Roman Catholic and Protestant Christians who affirm the traditional creeds of the Faith.

He writes:

Nevertheless, all Orthodox, Catholic and Protestant Christians assent together to the great creeds of the first thousand years of church history, such as the Apostle’s, Nicene, Chalcedonian and Athanasian creeds. In these creeds the fundamental Christian view of reality is laid out…

What is Christianity? For our purposes, I’ll define Christianity as the body of believers who assent to these great ecumenical creeds… I am making a case in this book for the truth of Christianity in general – not for one particular strand of it. [p116-117].

From the above two statements we see that Keller makes no distinction between the Protestant faith and Roman Catholicism—he defends the whole Church, which includes the Roman Catholic Church, and not one particular strand.

In Keller’s mind, a Christian believer is one who affirms belief in the ecumenical creeds of the Faith, and this includes Roman Catholics. But Keller’s definition of Christianity is contrary to Protestant doctrine laid out in the Westminster Confession of Faith. (source)

HT: Discern The Time

Further reading