Being called the “son of God” doesnt mean that they believed Jesus was divine or God Himself. Check this link (Post # 12)
forums.catholic-questions.org/showthread.php?t=205710
How come John’s Gospel was the last New Testament writing to be finalised? Christianity says that the central aspect of this religion is to believe that Jesus is God. However, it took at least 60 years after Jesus’ death for the Gospel of John to be completed. Even so many of the Trinirtarian “proofs” can be argued.
I see that there could be one instance in John where He claims divinity (John 8:58). And two other times when he is called “God” (John 1:1; John 20:28).
No earlier New Testament writing never includes a clear apology of His divinity, only that He was the promised Messiah. If the apostles clearly knew Jesus was part of the Blessed Trinity, you think they would have made that more clear. Maybe they didnt understand as yet or the truth wasnt revealed to them as yet.
In regards to John 10:30, this isnt clear evidence that Jesus was saying that He was God. In John 17 Jesus asked that His followers may be one like Jesus and the Father is One. Are you saying that we would be part of the Trinity as well? He also asks that we may be one, just as the Father and Jesus are one. Now, if you are saying that the Jesus is God because He said He is one with the Father, that means you should say that we are gods as well.
biblegateway.com/passage/?search=John%2017:20-23;&version=31;