Why do Catholics consider Abraham our father in faith?
Christians consider Abraham to be the spiritual father of all those who have faith in the one true God because it was to Abraham that the promise of salvation was given (cf. Gen. 12:2-3) and because it was Abraham who had faith in God that he would fulfill his promises, even when it seemed that Abraham was being asked to sacrifice the promised fulfillment in his son Isaac
(cf. Gen. 15:1-6, 22:1-18; Jas. 2:21-23).
From the Catechism of the Catholic Church we read:
Abraham thus fulfills the definition of faith in Hebrews 11:1: “Faith is the assurance of things hoped for, the conviction of things not seen.” “Abraham believed God, and it was reckoned to him as righteousness” Jas. 2:23]. Because he was “strong in his faith,” Abraham became the “father of all who believe” (CCC 146).
Salvation Is from the Jews** by Roy Schoeman