Let’s tease out the elements in this:
*]I’m tempted to fornicate
*]“This is a bad thing - fornication is a sin
*]…and I know it is
*]…and I admit it is…”
*]"…It’s confession tomorrow - I’ll be fine…"
*]…“I’ll do it”
*]I go to confession
*]“Father, I committed fornication, yesterday”
[/list]I would not like to be me in that frame of mind
Because sinning with the intention of getting the sin absolved is itself sinful - and the sin is made worse if one realises what one is doing.
The sacrament of reconciliation is a worthless sham, if the penitent lacks true sorrow for sin committed - he will not have his sins forgiven if he abuses the sacrament in this manner; far from it: his guilt will be increased, because he is using a holy ordinance of Christ in a frivolous manner, and is committing a sacrilege by confessing sins without sorrow for them. And sorrow for sin includes all sins, leaving none of them out - either one repents for all sins committed; or is not repentant at all. What one is doing, is making a bad confession, and trampling the Blood of Christ underfoot. Sorrow for sin is so necessary for this sacrament, that without it, the sacrament does not exist.
This assumes, of course, that the fornicator has not repented by the time he goes to the sacrament. He is committing a sin by intending to fornicate and then to go to confession, so that sin needs confessing; but he will not be committing a sacrilege (see above) provided that he is sorry for all his sins (including his fornication and the sin of thought just described) by the time he enters the confessional.
To sin with the thought that one can be forgiven, is to presume that God will forgive one - & that one will have the opportunity to repent. God owes us:
*]nor opportunity to repent
*]nor the grace of repentance:
[/list]so such a thought is itself sinful & rash.
Obviously one can’t confess every sin one has ever committed - so the sorrow for sin includes being sorry for all sins. So if one remembers a sin after being absolved, that sorrow means one will not intend to do it, and that one will intend to avoid all occasions of it so far as, aided by God, one can. The point being, that absolution is valid only if one intends to avoid sin in the future - so absolution of a Christian who has no firm intention to turn from his sins, is worthless; we do not have to be successful in not sinning again: that’s blindingly obvious - but there must be the intention not to sin again, and reliance on God to help us to avoid it.
ISTM that we would have a far better understanding of sin if we avoid the sort of minimalism that requires us to keep clear of mortal sin and do little more than that; as if that were the whole of Christian life. Maybe this minimalism has gone - one can hope so
To go to confession in the frame of mind you describe is worrying; it implies one has forgotten that God is Holy, and can’t be deceived. It implies that one forgets that Christ died for our sins - and if they had that effect, they must be terrible indeed. The sacrament is not like a drive-through car wash - it’s a means of interior renewal, by the grace of Christ, by grace which He merited for us through His Passion, and which He secures for us by His unceasing intercession as our High Priest in Heaven. We have every reason to treat this sacrament with enormous reverence. And if we do what your description describes, we aren’t showing much reverence for it - if anything, we are showing the hatred we have for Christ, because we are treating Him as a deadly enemy. Which is not exactly compatible with loving Him, as He requires of us ##