Books like God exists by André Frossard

C.S. Lewis’ radio talks, later published as three books, are compiled in "Mere Christianity," a clear apologia that explores core Christian beliefs and ethics across denominations.

Karen Armstrong traces humanity’s lifelong quest to answer profound questions through the evolving concept of God, focusing on Western monotheistic traditions, especially Christianity.

This book deals with a limited aspect of religion. Any well-developed religion is a very complex entity which unites components of very different sorts. There is probably no living religion that does not involve a set of characteristic beliefs, some prescribed or recommended practices (public or private, or both), some characteristic feelings or emotions, and some institutions or social arrangements. In addition, religions usually involve their adherents in special forms of experience. With respect to the complexity that it generates, interest in religion is similar to other pervasive human interests and activities, such as those that generate scientific enterprises. For some purposes, however, it is useful to separate the aspects of a complex phenomenon and to discuss one or another of these aspects individually, so far as is possible. This is the procedure that I will adopt here. My discussion is aimed primarily at that element of religious interest that centers upon belief, with what one might call the noetic aspect of religion. Some of the other aspects that I have mentioned- most notably religious experience and, to a much smaller extent, religious institutions- are discussed, but only to the extent that I take them to be relevant to questions about belief. But, of course, the should not be construed to imply that these other aspects of religion are unimportant.