These passages are not problems for those who embrace the Bible as God's message to man.
It is clear who Paul is referring to in this passage- and he is NOT denying the deity of Christ in so doing.
John's noting what the disciples saw doesn't negate sola fide either. The disciples had faith that Christ was who He said he was and who Scripture testified He was. They were eyewitnesses, for sure. They were blessed. But it doesn't mean that they didn't have true faith. Remember, they had just buried their friend. You can hardly fault them for losing focus on who Christ was - particularly since they didn't seem to realize all of the full import of what He said until after it was all over. Yet, they did believe. Not just that he was alive. They could see that. But that He was the Christ, the Son of the Living God. God in the flesh. Their Savior.
Kosta,you know that God is everpresent and watching everything you do. Do you ever betray him? Ever sin against him? Well, you know who He is. You know He's watching. Don't you find it strange that you sin against Him knowing you are in full view of Him? I don't. Peter had a "human" moment. If Scripture were a man-made man-inspired set of documents, Peter probably would have had a cape and rescued Jesus from the Cross. Instead, we see him as quite fallible and quite forgetful. I mean good grief - he fed 5000 and the next scene they are fearing for their lives in his midst. People forget very quickly. Peter was no exception.
As to the bond-slaves of death comment that is an interpretation. The Old Testament Saints were saved the same way we are - by faith. They had a different spot in history. They looked forward to the promised Messiah, and we look back at him. Still, it is said that Abraham's faith was counted for righteousness (and yes, James says his works justified him - but again, with a protestant understanding of James this is no problem).
Human moment? Or disbelief? Could it be that +Peter's faith failed, as ours does? But, unlike us, +Peter has seen Him, ate with Him, and witnessed all His miracles. I think that's a bit different than our experience.