As the Gospels say in more than one place, neither Peter nor the rest of the disciples really got the message until after the resurrection. Hindsight being 20/20 and all.
Christians presently in free countries do not meet in catacombs.
Whoever said that Saudi Arabia was a free country?
That is really quite a different statement than "having no idea at all". I would tend to remember an occasion when I was specifically rebuked by my teacher. If they didn't believe Jesus why were they following him? Hadn't they witnessed Lazarus?
The catacomb reference is to compare "confess/deny" to "show/hide".
Whatever all these questions lead others to believe. I cannot judge, condemn, criticize, or in any other way belittle the Apostles.