I have heard many people attempt to articulate the “content” of “saving faith,” usually in terms of the doctrine of justification.
It often comes off as overly complicated and (honestly) pretty weak compared the simple and profound definition found here.
For the author of Hebrews, saving faith is no mere intellectual assent or even “confidence” in any doctrine in and of itself. We find that
...faith is the assurance of things hoped for, the conviction of things not seen...by it the people of old received their commendation... (Heb. 11:1-2)
What is saving faith?
Saving faith is trust in a person. Saving faith is trust in God, that he is who he says he is and will do what he says he will do.
These people of old did not know all the details of the faith that saved them…but they still trusted that God had a plan. God began to reveal his plan with Abraham, and the Abrahamic covenant of faith still stands, gloriously fulfilled.
People were saved through faith ages ago, and people are saved through faith now.
All because of Jesus.