What is it about the major western worldviews especially Christianity and Sciecnce that Nietzsche considers?

Question

nihilistic?

also how does the notion of nihilism relate to the idea of the "Death of God."

Answer 1

That they are all fundamentally and fatally flawed at the core. That a deep enough evaluation will uncover the fact that they are all completely unsupportable against one another.

Once mankind in general realizes the above...and has nowhere to turn...the only result is nihilism. The last stand against nihilism will most likely be the resistance to admit that there is no god. That final realization will most likely be expressed as, "GOD IS DEAD........."

This will be the last hold out belief before mankind falls to nihilism.

Answer 2

In addition, to avoid the crushing nihilism that God's death will produce it will be necessary for some to 'cross the bridge' and become ubermenschen.