Perhaps the greatest contribution to christian orthodoxy made by irenaeus of lyons was his insistence that

There is only one God

St. Irenaeus is considered to be the among the greatest Christian theologians. He was concerned with Christ as the fulfilment of Old Testament prophecies. He contrasted Christianity with Judaism, in that the task of Judaism was to preserve the knowledge of the one God by establishing a solid national base for it among a single people, but the task of Christianity was to set out from that base to preach the Truth to all nations.

it will be innate immunity. good luck with your test : )!

oh and if you need . ask the question