That's the view of Mainstream Protestantism, and even some Protestant sects are starting to be less exclusivist.
To start with, as far as I'm aware the RCC teaches that some virtirious pagans end up in purgatory and eventually heaven.
Eastern Orthodoxy, which is the second largest denomination next to RCC, affirms postmortem salvation, and a good chunk of EOs think virtirious pagans were also freed at the Harrowing of Hell.
A good number of Anglicans also have similar ideas to these two denominations, minus the purgatory part. The respected Anglican writer, C.S Lewis, said "I think that every prayer which is sincerely made even to a false god, or to a very imperfectly conceived true God, is accepted by the true God and that Christ saves many who do not think they know him. For He is (dimly) present in the good side of the inferior teachers they follow. In the parable of the Sheep and Goats those who are saved do not seem to know that they have served Christ."
Speaking of which, there are hints in Scripture that some people are saved without knowing it, eg. the Sheep and the Goats (as C.S Lewis mentioned), Paul's statement in Romans 2:14-16, and, also from Paul, 'All Israel will be saved'. Of course, prooftexting doesn't do anything and there are legitimate objections to disputing these verses as inclusivist, but the fact that there's enough ambiguity about it says something.
Re: Lake of Fire, there are several interpretations about that passage. To start with, there is annihilationism, which says that the fire destroys souls, and purgatorial universalism, which says the fire cleanses souls. Even certain branches of eternal concious torment don't think the fire literally burns and tortures the unbelievers. It's a common thing to say that hell is just seperation from God, while the Orthodox position says that heaven and hell are the same place and that hell is just those who hate God being unable to comprehend His love.
It's fun pulling all of this out when people misunderstand the Christian view of salvation, you know? Really fun.