“Can someone confirm that presbyterians are indeed supposed to be Christian?”
They were. Its important to note there are two main Presbyterian denominations. This story is about PCUSA which has been taken over by liberals. At the individual church level there are good people who just haven’t paid attention to what their leaders are doing.
Presbyterian Church in America (PCA) is much more Bible based.
...and allow me to add for this context, the PCA is also solidly anti-abortion. The PCUSA has been careening down the slope of heresy for multiple decades now.