A contradiction?

Henri Nouwen wrote "that God is love and only love, and that every time fear, isolation, or despair begin to invade the human soul this is not something that comes from God."

I find it difficult to reconcile this stance, which I would very much like to accept, with the "mean" concluding words of Psalm 95, read each morning in monasteries around the world:

[God] said, "They are a people whose hearts go astray
and they do not know my ways."
So I swore in my anger,
"They shall not enter into my rest."

Objectively speaking, these do not seem to be words of unconditional love, but of a love that is conditional. The "anger", the denying people "[entry] into my rest" – these are words that evoke the "fear, isolation, or despair" that Nouwen asserts are "not something that comes from God".

Or could the psalmist be mistaken in attributing these thoughts to God?