I think Jesus tells us that there is more to faith than just belief in Matthew Cha 7:
The Two Foundations.
“Everyone who listens to these words of mine and acts on them will be like a wise man who built his house on rock. The rain fell, the floods came, and the winds blew and buffeted the house.s But it did not collapse; it had been set solidly on rock.
And everyone who listens to these words of mine but does not act on them will be like a fool who built his house on sand. The rain fell, the floods came, and the winds blew and buffeted the house. And it collapsed and was completely ruined.”
The thing is most people don't act on them, and after the cross Jesus revealed to Paul the Gospel of the Grace of God that was even for the gentiles, imagine rejecting that and pretending you are still pre the cross and Jesus hadn't died for the sins of the world, Imagine rejecting the blood atonement, or trying to obey the Law and repent of your own sin that could be a fool or someone that is blind or maybe as Paul put it bewitched, So how do you "act on" when Jesus said to Love, and no greater love is there than a man lay his life down for his friends as we are talking on the forum we haven't done that lately, so yes we are to build a solid foundation = 1 Corinthians 15
Because Jesus said
I am the way, the truth, and the life: no man cometh unto the Father, but by me.