Luke 21:16 You will be betrayed even by parents, brothers and sisters, relatives and friends, and they will put some of you to death.
When Jesus was talking about the end of times, He used fairly strong words warning of betrayal and fighting on all fronts.
What He is trying to get over is that we cannot depend on this earth to give us the truth; the truth only comes from God.
Our earthly friends and family will probably let us down at some stage in our lives, but God is not going to. Yes, we may let Him down, but He will never let us down!