I am not Catholic, so I don't know much about their way of doing things. It seems to me the Ten Commandments are rather straightforward. What is this about the third commandment being a direct contradiction of the 4th?
Prophecy, specifically...
KJV Daniel 7:25
25 And he shall speak great words against the most High, and shall wear out the saints of the most High,
and think to change times and laws: and they shall be given into his hand until a time and times and the dividing of time.
... Informs us that there would be a power who would think to change times and laws. We know that in the world of politics, empires and nations all alike change and establish laws according to their particular agendas, whether in democracies, tyrannies, oligarchies, or kingdoms... Thinking to, and actually changing law is no big deal. So this prophecy had to be about something more than day to day law changing as in the politics of a nation. And that the above power only
thought, but didn't actually
accomplish any changes, is also pertinent. God is here warning and talking about a power that would
think to change
His laws, in particular the ones He wrote on stone. Of course no-one has the power or the authority to change God's laws, though they may think about it and even take steps to inaugurate such an action, but such intent is a vain enterprise and God will not be moved from that which He established Himself.
The Catholic catechism, like the Bible, lists 10 commandments. In the catechism however the second Commandment with respect to graven images has been removed. The number 10 is retained by their dividing of the 10th into 2, thus moving the 3rd to 2nd, the 4th to 3rd, etc etc. They also in the 5th century officially changed the day of rest from the Sabbath on the 7th day, to the 1st day, Sunday. The Sabbath had been kept up to that time by nearly all churches outside of Rome and Alexandria, which has been attested to by many historians. This change is the day of rest was enforced by the Papacy over the centuries, through church councils and persecution of dissenters, and bequeathed to protestantism, the reformers not coming fully out of the church until the 19th century
Thus the little horn
thought to change times and laws. The times can not only be connected to the Sabbath/Sunday issue, but also to the hermeneutic by which those that read scripture were to understand prophecy. Until the 16 century most scholars used the historicist method off interpretation, and in doing so the reformers were able to accurately identify the Catholic Church as fulfilling the prophecies of Daniel and Revelation, one of which is referred to above, although as I said, that the tourneys didn't recognize. (There are more than 10 specific details or criteria that the Papacy fulfills to the letter). Those prophecies identify the Antichrist that would persecute God's people, and so it was.