…continued & ended]
We cannot in the strict sense merit eternal life - it comes purely from grace: yet it is our vocation by reason of our creation as men. That, is a paradox - and it is as well that it should be.
To love God is a need for man - yet it something which God commands: another paradox.
God is the Author of the whole of our salvation - yet we are commanded to “make [our] calling and election sure”: - a third.
God is One - yet God is Three: another.
The plan of the Most Holy God, Who is too pure of eye to look on evil, is to save sinful man: another. It is the creative Love of God which bridges the difference between His perfect Holiness & Being - and our lack of being, by being sinful . IOW, to justify us sinners, is as fully an act of creation as the creation of the world.
that Jesus is “made sin” on the Cross, and is “accursed”, while being that Son Who was infinitely well-pleasing to His Father in Heaven: is another
God is Grace from first to last. So Christians are under no law at all - which is exactly why we are under a far more stringent law than ever the Pharisees were: for our righteousness must exceed theirs. For God commands of us what we cannot give: total and unlimited and universal and unceasing love of Him, without any reserve whatever. This is impossible: God alone can do it - legalism OTOH is easy. And because we cannot do this, it is absolutely necessary for us to do it. In Christ, we can - so we do good works because we are in Christ - not so as to stay in Christ, still less to come to be in Christ. Grace is so far from being opposed to works after justification, that it is their essential source, the very thing which causes them to flourish. It goes without sayinng, that no work of man can even be thought to justify the unjustified: for God has provided for that already

by predestining us in Love to be heirs of salvation in Christ. Again, the Praise is His - not ours.
And so on

Everything, without any exception whatever, is wholly of grace. Including everything in the Church.
That is some of the detail of how works relate to being Catholic - it’s just one corner of one of the countless paradoxes of Christian believing. ##