I'm out of practice on these, too

I'm putting together an Excel sheet that'll allow me to easily set up cryptograms. Wanna try my first effort? (I can't remember the last time I made one of these. Be kind.)

ABC = THE, and punctuation marks are hints. I don't think this requires a clue.

MA MW T ATJC ASJG HZ TR MGMSA, XNJJ SX WSNRG TRG XNDZ, WMKRMXZMRK RSABMRK.