Before World War I, religious beliefs did not contradict science.
Science and technology in the last decades of the 19th century and the first of the 20th grew at a speed never reached before by Humanity.
The war took advantage of it with greater or lesser fortune. This was the first great mechanized contest. The development of engineering gave birth to new weapons, but also to the creation of ambulances. The advances in the laboratories allowed to create deadly gases and more powerful pumps; although new drugs to mitigate pain and antiseptics also appeared. And medicine used, for the first time, professional nursing in the front and its new prophylactic methods.
All these advances gave science the possibility of proposing answers to questions that were previously only left to the will of faith. For that reason, from that moment, science began to enter into issues that religion wanted to prohibit or reserve for itself, contradicting it in most cases.