Is the Church of The Holy Cross near a T station? I would like to come by some time but I travel by public transportation from Cambridge MA.

The Silver line (bus that acts like a train) has a stop across the street. You can pick it up at Downtown Crossing. Otherwise, take the Orange line to Tufts and walk ~15 minute (3/4 mile) down Washington. Back Bay is a similar distance and Broadway is slightly farther.

I believe broadway on the red line and tufts medical center on orange are also both close

I believe the closest T Station might be Back Bay Station. That's about a 15 minute walk to the Cathedral. There are buses, but I'm not sure where you would pick that up.