The Fourth Lateran Council, in the 13th century, decreed that communion must be taken at least once a year. There is a very good and detailed article on it here;
http://www.newadvent.org/cathen/06278a.htm
And from scripture,
The mass in scripture
Heb 10: (all emphasis mine)
Heb 10:19-31 RSVCE - A Call to Persevere - Therefore, - Bible Gateway
19 Therefore, brethren, since we have confidence to
enter the sanctuary by the blood of Jesus, 20 by the new and living way which he opened for us through the curtain, that is, through his flesh, 21 and since we have a great priest over the house of God, 22 let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water. 23
Let us hold fast the confession of our hope without wavering, for he who promised is faithful; 24 and let us consider how to stir up one another to love and good works, 25
not neglecting to meet together, as is the habit of some , but encouraging one another, and all the more
as you see the Day drawing near. 26 For
if we sin deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, 27 but a fearful prospect of judgment,and a fury of fire which will consume the adversaries. 28 A man who has violated the law of Moses dies without mercy at the testimony of two or three witnesses. 29
How much worse punishment do you think will be deserved by the man who has spurned the Son of God, and profaned the blood of the covenant by which he was sanctified, and outraged the Spirit of grace ?30 For we know him who said, “Vengeance is mine, I will repay.” And again, “The Lord will judge his people.” 31 It is a fearful thing to fall into the hands of the living God."
Unpacking that
deliberate Failure to meet on
the Day ,= Sunday the Lord’s day, & it’s already a sin with huge consequences to deliberately miss, ONCE SOMEONE KNOWS THE TRUTH.
What are they doing when they meet?
“
sacrifice for sin ”, &; “
blood of the covenant ” = the words Our Lord spoke instituting the
Eucharist
Matthew 26:28 ,
Mt 26:28 RSVCE - for this is my blood of the covenant, - Bible Gateway
Mark 14:24 ,
Mark 14:24 RSVCE - And he said to them, “This is my - Bible Gateway
i.e. They are celebrating the Mass,
THAT’s why those who deliberately fail to celebrate Mass (the Eucharist) on Sunday
after being given the knowledge of truth,
THEN
◦ no longer remains for
Them , a
sacrifice for sin and blood of the covenant
◦ They Spurn the Son of God
◦ They outrage the
spirit of grace
◦ a fearful prospect of judgement awaits Them
◦ and a fury of fire will consume
these adversaries
Q:
Does that sound like it’s only a suggestion to attend Mass on Sunday, or a command?
Does it sound like a venial sin to deliberately miss Mass on Sunday or a mortal sin?