In the late first early second century (AD 90-102), John writes a series of letters directed at the churches residing in Ephesus. Other writings from John include a firsthand account of the life of Jesus from his own perspective (Gospel of John). Another expresses a vision given to John in his exile on the Island of Patmos (Revelation).
It appears from the letters John writes to the church there was some false teaching happening. Denial of Jesus' divinity (I John 2:22; 5:1, 5) and a rejection of their own sin (I John 1:8, 10). John calls these false teachers "antichrists" because they denied Jesus as both the Messiah and Son of God (I John 2:22, 26).
The first-century followers residing in and around Ephesus seemed to be getting some harassment from those who split from the church. John writes his letter to remind these Christians that their faith in Jesus is not vain.
In the first four verses of John's first letter, he spends time reassuring these Christians that what they believe about Jesus is not unrealistic.
"That which was from the beginning, which we have heard, which we have seen with our eyes, which we looked upon and have touched with our hands, concerning the word of life—" (I John 1:1)
This passage mirrors the first words of John's gospel account by attesting to the authenticity of Jesus' life all the way from the beginning of time. John had personally known Jesus, he heard him teach, he saw him walk and do miracles, and he touched Jesus with his hands (I John 1:1).
In our world today, people are as quick to dismiss Jesus as they are to disregard the credibility of those who witnessed Jesus firsthand. They assume he was just a very influential man or a great religious figure and do not take the time to dig in and do the research for themselves.
The challenge for all followers is to share their faith no matter the circumstances. Regardless of what the world believes about Jesus, we need to share him with this lost world. Deep, meaningful conversations about the Scriptures and their authenticity need to happen. But they won't if we are afraid of being rejected. Humanities' natural instinct is to go with the grain to avoid being outcast, but when has that ever made an impact? Does God just want some people to be saved?
Christian, do not be afraid to share your faith with others. The world needs the light of Jesus more than we know.