From only the human POV, the elect are marked at regeneration. Some say the sinner's prayer falsely, as the article I posted to you, after your post here, shows. On your side, I don't know how or if people are "falsely" Baptized. You know how I feel about (infant) Baptism, but of course that doesn't stop the Catholic elect from later coming to the saving grace of Christ (perhaps at Confirmation, an idea I like). At that point, the Catholic "COULD" have assurance, but of course this would never happen because the person would have to throw out Catholic teaching. :) Not happening!
So, for either Catholic, Orthodox, or Protestant, the mark is ACTUALLY there at the time of faith for the elect. Whether any of us can or do know it is a matter of difference. Our view is that, for the elect, the first installment DOES guarantee the future actions.
Like I said before, brother, we have a different definition of "saved". Yes, we are "saved" at Baptism, but it is in the sense that we are healed. HOWEVER, this doesn't mean we won't get sick again. This would preclude free will! Thus, our idea of "saved" does not include "eternal heaven". When we discuss eternal heaven, we realize we (Catholics) individually do not know - it is God's choice and we do not know absolutely His mind on the subject. We can have a good idea today, and that's about it. Thus, there is no problem with a person Falling Away/Never was saved to begin with concept. I am of the mind that even people who say the sinner's prayer SINCERELY and would give their life to God at that moment, doesn't mean it will matter to them when they run into something that rocks their faith 5 years into the future.
To us, Baptism is for the remission of all sins. It makes us children of God. It grants us sanctifying grace - if we were to trip and fall and die while leaving the altar, we'd end up in heaven! Baptism does NOT eliminate concupiscience, however! We still can be tempted to sin, although God offers His aid during such times (which we CAN ignore). Thus, a person, despite being Baptised, can still fall away, can still require God's graces again - just as the Prodigal Son needed his father's healing touch again to "know" he was welcome in his father's home. Just like the young man, we need to know we are back in our father's good graces and restore our relationship with him. Sin destroys this relationship. Reconciliation restores it. Thus, we don't have this idea of "healed/never healed to begin with".
Our view is that, for the elect, the first installment DOES guarantee the future actions.
This is God's view, a view that we will never know until our subsequent judgment. Thus, there is no point in placing yourself falsely into such a group with absolute assurance. Yes, the elect will persevere. The problem is that HUMANS place THEMSELVES into this group without considering that they MAY fall away. Men too easily convince themselves of things that are beyond their ability to know.
Regards