“So it’s your official position that one cannot lose one’s salvation,”
No, “once saved always saved” is not an orthodox Christian belief. That is a heretical belief which only Protestants hold.
“and that one can KNOW for certain that one is saved”
No, “absolute assurance” is not an orthodox Christian belief. That is a heretical belief which only some Protestants hold - not all.
“and it is not incumbent upon one to help save oneself through “sacraments”?”
Only God helps us through the sacraments. They are HIS works not ours.
“If that’s truly your position, you’re the first Catholic I’ve come across who believes that salvation is secure and based on grace and faith alone.”
Salvation by grace alone does not imply - even remotely - the heretical Protestant doctrines of absolute assurance, or once-saved-always-saved.
So you think verses which clearly state the believer is secure are heresy? Guess that’s why we will never agree. I’ll stand on God’s Word: John 10:28, John 6:37-39; and pretty much all of Romans.
Scripture states that it is through faith, not works — Ephesians 2:8-9
In context, the Scripture which speaks of the two together, and which so many Roman Catholics have misunderstood, James 2:14-26, clearly demonstrates the difference between a true, saving faith, and the type which demons possess. Works are not what save, but rather demonstrate the type of faith one has.
Nothing more really need be said. You have demonstrated you cling to the man-made institution of Catholicism; I to Scripture and God’s Word. No middle ground there that I can see. You may continue a monologue if you wish, but continuing this back and forth is unprofitable and I have better things to do, frankly.