Is it a Sin to Kneel in Church?

Of course not, and I might add if the priest were praying at Mass he wouldn't even notice what his parishioners are doing...

From the LA Times:

It's AD 2006, and the peasants are much brighter than they used to be. So this question nags at me: Is it really in keeping with the worshipful spirit in an enlightened age that a priest would chastise some in the flock — grown men and women — for kneeling in church during a point in the Mass?

I mean, if you can't kneel in church….

The word "chastise" is too tame; the priest at St. Mary's by the Sea says it's a mortal sin and has invited 55 offending members to leave the church.

They have declined, although I can't imagine why.

As reported in Sunday's paper by The Times' David Haldane, the to-kneel-or-not-to-kneel issue involves a particular moment in the Mass after the priest holds up the chalice and consecrated bread and invokes Christ. For centuries, Roman Catholics knelt after that part of the liturgy. In recent years, however, the Vatican allowed local dioceses to eschew kneeling, and the Orange County diocese has backed the no-kneeling rule during that part of the Mass. Parishioners still kneel during other parts of the service.