******************** Noooooo !!! Do not unplug the speaker from the power amp. 

You should never run a tube amp with the speaker unplugged.  Without a load:  there is ia high probabllity that you will damage your amp's output transformer and  it will need to be replaced.  This will cost you mucho $$$.

In some cases, the tube amp will have a dummy load that kicks in when the speaker is unplugged but these are in the minority and I cannot confirm whether the Boogie has one.  Don';t take the chance unless you can confirm this.

If you think this through:  even with the speaker removed you would stilll  not be hitting your bases.   You could run the Boogie Preamp in the FX Loop of the Pod (as is standard with 4CM) but then the output would not actually go through a power amp and speaker simulation.  There is no generic power amp/speaker model on the pod so you would find your tone might be a bit on the thin and anaemic side when you DI-d it.

If you cannot reduce the Boogie's volume enough to make it sound good at low volume:  I would think about:

1)  A power soak between the Power amp and speaker to reduce the overall volume.  The power amp could cook as much as you want at a reduced speaker volume and may do the do

  http://en.wikipedia.org/wiki/Power_attenuator_(guitar)

2)  Another smaller amp for church.

3)  Use the Pod modelling as intended and work up some good modelled tones for DI into the church PA.