Is missing Mass still a mortal sin?
The easy answer is yes –if by missing Mass you mean deliberate and willful negligence of your Sunday obligation. This includes taking trips you know will prevent you from attending Mass (when you have an option), sleeping in because “Sunday is my only off day”, skipping because of work, play or any other activity that is within your will to control. Situations that are beyond our control will always happen and we’re all smart enough to know what those entail… there’s no need to belabor the point.
So… Why is it a mortal sin? A mortal sin is an action that 1) Involves Grave Matter 2) Is done with full knowledge, and 3) Is done with full consent. We’ve established above what full knowledge and full consent would look like in the case of skipping Mass. But is it a grave matter?
Well, let’s look at it this way. God became Man. God. He who existed before all time. He who called time into being. He who had no beginning and will have no end. He whose size dwarfs the stars and in whose breast the universe is nestled. He who holds us in existence by a thought. God. He condescended to become what he created. He became man. But His humility knows no limits! Even though He created us and was now one of us, He was not close enough to us. NO. To be even closer to us, to enable us to unite ourselves to Him, He became food. He became bread. He became that which we eat and which nourishes our bodies.
This is the humility of God: To offer Himself to us under the unassuming appearance of bread. He offers Himself to us at every Mass. So, imagine telling Him, “Thanks, but no thanks. I’d rather go camping.”
Walking away from God in order to indulge in a secular happiness is the definition of a mortal sin.