"Certainly the Christian religion is an antiquity projected into our times from remote prehistory; and the fact that the claim is believed - whereas one is otherwise so strict in examining pretensions - is perhaps the most ancient piece of this heritage."

This webpage contains many quotes said by Nietzche regarding religion and philosophy. A problem with this source is that although it provides direct quotations from Nietzche, it doesn't provide as much information as would be desired.

"His work crosses the boundaries of philosophy, theology, psychology, literary criticism, devotional literature and fiction. Kierkegaard brought this potent mixture of discourses to bear as social critique and for the purpose of renewing Christian faith within Christendom. "

This source is a biography of Kierkegaard which speaks not only of his views on existentialism and other topics such as Christianity. A problem with this source is that it doesn't focus on the topic of existentialism so it is difficult to find focused information on the topic.

"'Existentialism', therefore, may be defined as the philosophical theory which holds that a further set of categories, governed by the norm of authenticity, is necessary to grasp human existence."

This source is an in depth definition of what existentialism is. It also provides further reading in to other topics related to existentialism such as Nietzsche and Sartre. A problem with this source is that it talks about such a broad topic of things that it it is difficult to find specific information