Before the big moment where Jesus died on the cross on behalf of humanity, Jesus prayed for the disciples -- and all believers too. In closing, Jesus talks about how he declared His credentials to the disciples and other believers at that time.
In particular, Jesus talked about how unlike the world, Jesus knew the Father and how the Father sent Jesus, and so do the disciples (17:25). We know that Jesus talked about his credentials -- especially with His link to the Father -- throughout John, and while some people (i.e.: the Pharisees) rejected it, others (i.e.: the disciples) embraced and accepted it. Additionally, the purpose of declaring Jesus's name is that "the love with which [the Father] loved [Jesus] may be in them" (17:26). Whenever someone (this could be YOU) realizes that Jesus loves them in spite of their screw-ups and accepts Jesus as Lord and Savior, they can experience Jesus's love.