If that's his understanding, which I believe it is, then his decision would not be sinful. However, as a matter of fact, Christians are obligated to attend Mass every Sunday. I've presented my arguments here. You're free to present yours.
If that's your understanding, which I believe it is, then your decision would not be sinful. However, as a matter of fact, only Roman Catholics are obligated to attend Mass every Sunday.
Catholics are required to attend Mass, Aquinasfan. Christians aren't. We go to church because we want to be obedient, for sure, but I go because I love to go. Not all Catholics are christians and not all christians are Catholic.
It is well documented that the emperor Constantine made it illegal for "Christians" to observe the Sabbath, because he didn't want them to practice the same worship as the Jews.
I believe that Jesus observed every Sabbath as well as every Feast of the Lord, and even Paul made sacrifices in the Jewish temple on the Sabbath. Why do Catholics prefer to follow the decrees of a pagan emporor, rather than to do as Jesus did and keep the Sabbath Holy?