What did Martin Buber mean by emuna in his discussion of Judaism?

In his work Zwei Glaubensweisen (1950), Martin Buber distinguished between two religious types based on their approach to God. He used the Hebrew term emuna to describe a relationship of trust, characterized by mutual confidence between God and man.1

For Buber, emuna represents the essence of Judaism, aligning with his philosophy of the I–Thou encounter, where God is met and addressed directly rather than treated as an object of thought. This stands in contrast to the Greek term pistis, which Buber associated with Christianity and defined as a belief in the factuality of specific events within salvation history. While Buber identified Judaism as the classical example of emuna, he acknowledged that historical expressions of both religions often contained elements of the other.1