I'm trying to get some background on the namesake for St. Mark's Place.

Both 'Naming New York' by Sanna Feirstein, and 'the Street Book' by Henry Moscow are pretty noncomittal, saying only that the STREET was named for the CHURCH.  Nothing about St. Mark. 

It's impossible not to think of the second Gospel (Matthew, Mark, Luke, John) but was the Biblical Mark a saint?

-D