You are factually incorrect. Also none of this is relevant. By law the President has broad discretion in these matters, as the SCOTUS noted. And it might just be possible that the President has information that we in the public don’t have. Simply put, President Trump has the authority to have done this and it was legal.
The president takes an oath to abide by the Constitution, and that includes the 14th Amendment and its "Equal Protection Clause" that is there to prevent religious and other forms of discrimination. And this is also what the 1st Amendment sorta mandates with its "Establishment Clause". Trumps first decision was to ban all Muslims, not just some, and that was shot down by the courts, and rightfully so, because it does indeed violate the Constitution.
And now he is saying that he can "send them ["illegal immigrants"} back where they came from" without a judge or court procedure, which is also a violation of the Constitution according to previous SCOTUS decisions ("due process", which also applies to non-citizens).
And this is the guy who you support.