They think a bunch of slogans is deep thinking.
But that’s just one symptom of a spiritual issue.
In their souls they KNOW the Lord is preserving them by means of a promise. The trouble is that they are getting arrogant about it. They think they deserve the wonderful lot they have (for the most part) just because they are so wonderful themselves. They ignore the fact that the often-unrequited love from God is keeping them around and even prospering them.
Christians didn’t cook up this idea. It’s in the Hebrew scriptures.
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>> “In their souls they KNOW the Lord is preserving them by means of a promise.” <<
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That promise is for his believing remnant, the “people for his name,” not everyone that dares to call themselves an Israelite.
He destroyed an entire generation of them in the Sinai desert for unbelief, before they were allowed to re-enter the land.
Perhaps they do believe as you said, but arrogantly, and falsely.