How did Martin Buber use the term pistis when discussing Christianity?

In his work Zwei Glaubensweisen (1950), Martin Buber distinguished between two religious types based on their approach to God. He used the Greek term pistis to characterize Christianity, defining it as a belief in the factuality of specific events within salvation history, such as the life, death, and Resurrection of Jesus as described by Paul.1

This contrasts with his use of the Hebrew term emuna, which he associated with Judaism and described as a relationship of mutual trust and confidence between God and man. While Buber identified these as distinct religious types, he acknowledged that historical Christianity contains elements of emuna and historical Judaism contains elements of pistis.1