Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not. (1 John 3:1 KJV)
This verse is worth looking at a second time. This time my focus is on the last line: "therefore the world knoweth us not, because it knew him not."
If you need evidence that the Bible is true, this is a good place to start. Just look around you. How are Christians generally portrayed in Hollywood movies and television sitcoms? Are they portrayed in a favorable light? No. It's almost always in a negative light.
Take a look at how Christians who support the traditional Biblical view of the family are treated in the news and by those who are not tolerant of that view? They are boycotted, sued and put of business in some cases.
Look how the radical Isl*m*sts are treating those who claim to be Christians in the MIddle East right now. They are driving them from their homes, torturing some and killing others publically for all to see.
Look what happens to the Christian school child who dares to stand up in class and proclaim the truth. They are rediculed into silence most of the time.
All of the above scenarios all give evidence to the truth of God's Word. God is kind and merciful to tell us the truth so we do not need to be surprised and caught off guard. The world does not know Him and therefore they will not know us. When we show people the truth of God's Word, they react as if we are an alien from another world. We should not be surprised. If they knew God, then they would not react in these ways toward us.
This knowledge should first of all be a comfort to us because God knows and understands what Christians will have to deal with. Seccondly, it should comfort us to see that their reactions are evidences that the Bible is true. Thirdly, it should comfort us that God loves us enough to give us forwarning of how the world will react toward us. To be for-warned is to be for-armed.