Fiance lies to his family that he is a religious Muslim, is this a bad sign?

He tells them he goes to the mosque every so often to make them happy. He says he’s religious when he isn’t. He's told me if his family ask what religion his children will grown up in, say to them they’ll follow their dad.

Is this a red flag?

Fiance lies to his family that he is a religious Muslim, is this a bad sign?
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