All languages work in a fluid manner. Words are defined not necessarily by their dictionary definition, but by the cultural, contextual definition. So when Peter says that Jesus knows “all things”, the modern reader may be inclined to think Jesus was omniscient, but other scriptures are very clear that Jesus did not know everything possible that could be known. “All” is being used in a figurative sense, meaning “a large amount”.
Another example in the Bible in which the Bible explicitly explains that “all” does not mean “all” is found in 1st Corinthians:
1Co 15:27 For “HE HAS PUT ALL THINGS UNDER HIS FEET.” But when He says “all things are put under Him,” it is evident that He who put all things under Him is excepted.
This is very telling because Paul is taking it upon himself to explain that “all” is not all inclusive. Paul must have been under some impression that his figurative use of the word “all” would be lost on some individuals. He explains that “all” does not include God.
The Bible contains figures of speech and there are no surefire rules of identifying them. As counter intuitive as it might seem, people have to know before they read a verse what the real meaning of the verse is. A much disputed verse for this type of controversy is John 3:16:
Joh 3:16 For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life.
Calvinism claims that God died for only the elect. This is the concept of “limited atonement”. In order to hold this position, John 3:16 is required to be limited only to a select group of people. “World” they claim means mankind in general, and “whoever” is interpreted as only believers.
How do we “know” this is false from the Greek grammar or context? In short: we don’t. But we do know from the rest of the Bible the character of God. God is relational, responds to his creation (including pagans), he is love, and he responds to individuals based on individual actions. Would God be so evil as to create people with whom it is impossible to love God? All signs point to no.
“All” does not necessarily mean “all”. We know the meaning of figures of speech not necessarily from context but from understanding of the entirety of the Bible.