Highly debatable. If you believe in a categorical imperative that to intentionally deceive another person is wrong, then lying by omission is still an immoral act. A Christian might also interpret the words of Jesus “Render to Caesar what is Caesar’s” as an imperative to comply fully with the law of the land.
If Jesus (assuming he existed, even, regardless of any sort of divinity) tells us that following the law is always the moral thing to do, then he was wrong.
I don't think it's all that debatable to say that deceiving people is categorically wrong, nor is it to say that it's immoral not to follow the laws of the land -- both are obviously untrue as absolute statements.
For extreme examples, would it be immoral to lie to the Gestapo about harboring Jews? Were people illegally helping slaves escape the American South being immoral?
This is something that first/second year philosophy students do debate.
They are not debating it.
> For extreme examples, would it be immoral to lie to the Gestapo about harboring Jews? Were people illegally helping slaves escape the American South being immoral?
If you believe in that categorical imperative, then yes. I’m not saying I believe in it or that Kantian philosophy is the only correct one. There are endless belief systems and philosophical schools of thought that can be used to answer that question, and they will have different answers for different reasons.