This is always a disturbing topic to me.
So you have two people devoutly practicing the Orthodox religion. One of them happens to have been a practicing Catholic years ago.
Both are happy in the Orthodox religion and fully embrace it.
But According to the Catholic Church, the former Catholic is completely wrong with God, while the other is right with God?? Even though they both are living according to the same religion, living a very similar lifestyle, etc?
This makes no sense to me. All of life is a long spiritual journey. Some people spend time in many different religions and philosophies. It seems what counts is your destination, and where you are now. Why does the past matter so much as to rise to the level of mortal sin??