I don’t think a memory palace is necessary the best primary method for such a memory task. I imagine the reasom you want to memorise Mark’s Gospel is because it has great meaning to you. I even go as far as speculating that you have already read (most) of it and can give a summary from memory. This will make it the task much more likely to succeed.
jigsaw puzzle method
When you are solving a jigsaw puzzle, it is often useful to start with the edge pices, and whatever pieces are easiest. That way you create a framework, that will help with putting the other pieces in it’s proper place.
this method applied to your memory task may be something like:
- memorise the best summary you can find or make;
- memorise the first and last sentence of each chapter/paragraph;
- memorise sentences, that for whatever reason are important or easy to remember;
- always continue with whatever progression is the easiest.
Of course you always combine this with using a memory palace.
If you succeed in doing this, you will have done something very special.
Best of luck.