Not all Islamists are Jihadists, but all Jihadists are Islamists. Islamism is the ocean in which the terrorist jihadis swim.
You can ask a secular question of an immigrant. Asking about a person's adherence to sharia is a reasonable, secular question.
I would be perfectly happy to omit a person who had an Islamist interpretation of sharia from the list of immigrants to my country. I suspect many Americans would too. The problem is getting a truthful answer.
If you want to live under Islamic law, here's a list of countries to which to apply: Saudi Arabia, Sudan, Iran, Iraq, Afghanistan, Pakistan, Brunei, United Arab Emirates, Qatar, Yemen and Mauritania. Enjoy!