The Gospels pretty clearly teach ALL the apostles (except Judas) were saved during Jesus' years of ministry, not afterwards. Thomas believed in the resurrection by sight - it doesn't say he was saved by sight. Every believer who ever lived - including all those that were around the cross - were saved by faith. Viewing Jesus' death doesn't tell you He died for your sins, that He paid the whole penalty, that He was righteous, etc. Those are things that must be accepted by faith - and faith is believing what God has said about something. When Jesus told His disciples He was going to lay His life down for them and die for their sins, they believed Him - even if there were some things they didn't understand about the resurrection (until after the fact).