It is interesting that we find here in II John, and it is only one chapter, a very direct theological statement geared to speaking against a group of people called the gnostics. The gnostics didn’t believe that Jesus had actually come in the flesh. They didn’t believe that God could actually become a human. If you pick up this reading at vs. 7 we read a condemnation of those who don’t believe that Jesus is God in the flesh.
So today we have a number of heresies that people preach. There is the heresy of the prosperity Gospel where a preacher will say that God will bless you abundantly only if you give the church money in abundance. There is the heresy of legalism which states that we have to earn our salvation through certain works. The list can continue. There is also a common heresy even today which follows along with what John is addressing. Some want to differentiate God from Jesus. Jesus was a good teacher, a great human. God is God, how can Jesus be God? Jesus is God. There is no distinction. Jesus is God in the flesh.
There really is no wiggle room in debating the divinity of Christ. Jesus is divine. John was dealing with people who did not believe that Jesus was divine. I guess the more things change the more they stay the same.