I think it may be a misunderstanding on the word saved. Catholics should know that in the present tense they can generally tell you to a high degree of certainty whether they are going to heaven or hell (“If I was to die in the state I’m in right now then I am going to…”) because like I said, if someone has committed a mortal sin since their last confession then they would generally know about it.
However, the idea of ‘saved’, it’s a past tense word. So if taken under the Catholic idea of sanctifying grace, it’s like asking “have you ever been in a state of sanctifying grace before”. Of course then the answer is yes, because we are all in a state of grace immediately after being baptised. Of course no one would bother to ask that question, so when a Catholic hears the question “are you saved”, the way he might interpret it is not as “have you been in a state of grace in the past” but “did some event happen in the past that puts you in a state of grace forever”. The answer has to then be ‘no’ because while I’m alive it is always possible for me to go from a state of grace to a state of sin by mortal sin. Not until I die and find myself in either heaven or purgatory can I know that I am in a state of grace forever more.
Summary -
Past Tense - Have I (any catholic) ever been saved (ie, been in a state of grace) in the past - yes for every Catholic, we have all been in a state of grace at one time.
Present Tense - Am I in a state of grace now? Either yes or no, I can know which it is to a high degree of certainty. If I go to reconciliation and confess all mortal sins I can remember since my last confession, then I can say yes for sure, immediately after confession.
Future Tense - Will I be in a state of grace at time x? I hope so, and I can work towards it by avoiding mortal sin from now till then. But I can’t say for sure since I can’t predict the future.
Timeless present - Will I be in a state of grace now and forever? While I’m alive, no, I can’t say this for sure.
By the way, about full knowledge and consent -
You mention self-deception. That’s basically the same as making excuses, it’s like trying to fool yourself into thinking it’s not really wrong. That can’t change the fact that you really do know. In fact there are some things that all people know innately - like that murder is wrong, even atheists know that, because it is a part of natural moral law, buried inside us, in our conscience. Self decption and making excuses is no excuse. If you know it’s wrong, you know it’s wrong.
However, in cases of insane people, for eg, they are generally not consenting to anything they do. If your decision making facilities are not at their best due to illness, effects of substances, addiction, etc., then there can be mitigating circumstancews (some blame is removed) which can sometimes mean that the sin is venial rather than mortal.
Ah, you talk about the grace of God. The grace of God (sanctifying grace at least) leaves you when you commit mortal sin. God still calls you to repentance though.
You make it sound as if committing mortal sin and not repenting is almost impossible (because deep down we still love God and of course that’s going to bring us to repentance or else prevent us from really sinning - grave matters - with full consent in the first place). The thing is though that there are things that sometimes stop people from loving God, and all of a sudden mortal sin becomes easy to commit. Like some people become angry at God after someone they love dies. In this angry time they might well do something to offend God and not care. Only if they turn back to God later will they try to make repentance.
Or things other than anger can have effect as well. Eg, many speculate that Judas never repented, and the reason for this was his despair. They speculate that he gave up hope of ever being forgiven, hence didnt seek forgiveness and hung himself instead.
Despair, fear, anger, etc., many things can keep us from God.