Darwin's religious views

The concept of intelligent design, the question of free will, and human values are all affected by Darwin's work in the nineteenth century. Although, in his book, On the Origin of Species, he did not express his religious position, but it is believed that he gradually became an atheist as the result of the experiments he made and the evidences he found in nature. However, the views of Darwin on religion and the implications of his Evolution theory has still remained controversial. In my opinion, by looking at Darwin's Evolution theory, everyone can see that his theory has conflict with Christianity, God, and Bible. Nevertheless, during his life, Darwin himself went back and forth from one religious view to the other. Also, the spectrum of ideas at Darwin's time affected his religious views. There are a lot of letters from different people with different religious beliefs to Darwin and there are lots of answers to these letters from Darwin that can show his beliefs. On the other hand, it seems that Darwin did not want to express his religious beliefs because he believed that being a naturalist and being a religious person are two different things that cannot be mixed. Yet, his letter to Emma about religion, and his debates with different clergymen at his time demonstrates Darwin's doubt about intelligent design, God, and religion.