Someone told me that we sing with the Christmas Angels at every Mass. Is this true?

Yes. Christmas comes from the old English "Cristes maesse" meaning Christ's Mass. We see that at the first Christmas, there were angels and notice what they say:

• And suddenly there was a multitude of heavenly host with the angel, praising God and saying, "Glory to God in the highest and on earth peace to those on whom his favor rests."-Luke 2:13-14.

At Mass, when we sing similar words, we sing with the angels (although some like myself do not sound like the angels) and also give glory to God at Christ's Mass. We must always remember the Mass always belongs to Christ, but he allows us to participate in the offering of himself to the Father, through the Holy Spirit because we are baptized into him. So remember next time you are at Mass, you are singing with the angels at Christmas!