Most of my friends throughout my life have been Roman Catholic so I would welcome being told I am wrong about this.
An article I saw about 5 yrs ago stressed that the previous Pope said their issue with Protestantism boiled down primarily to two aspects: Authority to baptize and authority re: the eucharist/Lord'Supper.
That doesn't mean Catholicism hasn't had other doctrinal points of contention with Protestantism (hey, parts of Protestantism has doctrinal points of contention within other parts of Protestantism!)...
But you focused on the word "validity" -- but per that article...the only part that recent Catholicism has openly questioned Protestantism's "validity" is on the grounds of the Sacraments & the authority to practice them.
Catholics recognize that the Orthodox have apostolic succession. Except for some Anglicans and maybe some Lutherans, not sure any other Christian group has the same understanding as Orthodox/Catholics with apostolic succession.
As far as being destined for hell, Pope Benedict confirmed this:
“It follows that these separated churches and Communities, though we believe they suffer from defects, are deprived neither of significance nor importance in the mystery of salvation. In fact the Spirit of Christ has not refrained from using them as instruments of salvation, whose value derives from that fullness of grace and of truth which has been entrusted to the Catholic Church”
So if your Catholic friends disagree tell them to take it up with the Pope.
Freegards
Oh, they’ll tell you if they think you are wrong, katana. And everyone who is against them is wrong.
Katana, you are right. i have posted a link from the catechism of the catholic church. see #845:
“outside the Church there is no salvation (extra ecclesiam nulla salus)”
http://www.vatican.va/archive/ENG0015/__P29.HTM