Very simply- the Vatican, meaning the Pope, didn't forgive John Lennon of anything, in so far as I can tell.
I was under the impression that L'Osservatore Romano was the official newspaper of the Vatican. It is not. It is semi-official. I'm not entirely sure what "semi official" means, but it's enough to say the paper has a degree of independence that allows it to editorialize without direct consent from the Pope or his administration. I was also under the impression L'Osservatore Romano made some kind of statement of Lennon being forgiven by the R.C. Church, I do not believe it did so. I have been unable to locate the full article printed by L'Osservatore Romano, but from what I can tell, it nowhere grants forgiveness to Lennon as widely reported by various news agencies, but rather dismisses and downplays his blasphemous comments by noting his youth and sudden blast of worldwide popularity. A strange article with unsusual laud for a pagan band, but not a statement of forgiveness. I was wrong to have reported it as such.
I am very sorry to those Roman Catholics who were offended by my rush to judge the Vatican's alleged exoneration of John Lennon and will do better to be more accurate before posting something like this again. Please forgive me.