Roe vs Wade - The simple question that I do not understand

 I'm not American, so I don't understand their legal system. I've just been watching the coverage of protests from America about the overturning of the 50 year old decision by the Supreme Court to grant the right to Abortion. I don't want to get too deeply into the rights and wrongs of the issue, for the simple reason that I'm a man and it's not something I'd ever have to make a personal decision about. 

But what I don't understand is that I thought the law was the law and it rose above politics. As I understand it, Donald Trump appointed several very right wing judges, who cannot be sacked, who have re-interpreted a ruling that was made 50 years ago, by the highest court in the land. Now I am not a constitutional expert, but isn't this subverting the concept of an independent judiciary, which is not politcally motivated? Since the law was passed, we've had Republican Presidents such as Nixon, Ford, Reagan, Bush and Bush. Yet now, under a Democrat president, we get a decision made by a Supreme Court that due to a series of deaths of Judges, under a one term president, who was  unceremoniously booted out by voters in record numbers, a highly controversial decision has been made and due to the fact that Judges can only be replaced when they die, it is unlikely to be overturned any time soon. 

Regardless of what side of the argument you are on, any sane person would stand back and see the risks of this. I'm not saying the Supreme Court Judges are right or wrong, I'm not legally qualified in US law to pass an opinion. What I can say though, is if this ruling has stood for 50 years, and has only been overturned on the whim of a Judge appointed by an insurrectionalist president, to me it fails the 'sniff test' in a big way. Feel free to tell me why I'm wrong, but please don't say "It's the will of Jesus". I'm a Roman Catholic and if this were true, then we'd never have had the Roe vs Wade decision in the first place. I thought the whole basis of the law of the land in the US is that State and Religion are separated. It is hard to square that premis with the decision