The claim was you can’t have a religious test on immigration.
Islam needs to be put in a different category than ‘religion’. Any group that wants to kill nonbelievers and take over countries should be considered a subversive group hiding behind a religion.
Of course even little school kids used to know that the only “religious test” mentioned in the Constitution is for the Presidency, not immigration. But that was back before the communists took over all the schools.
Given how few Syrian Christians have been allowed in, I'd say that a religious test already exists. The only difference is that this administration has been silent about it.