In John 16: 16-31 we read that Jesus warned his disciples about future opposition because he did not want them to be surprised by the damage that was to come. He told them that they would be expelled from the synagogue because of Jesus.
We read that the disciples were saddened by Jesus' departure. But Jesus' departure from them was a major step in their growth as his disciples. We later read that Jesus promised to send the Holy Spirit. He also explains how the presence and work of the Holy Spirit is actually better for believers than the physical presence of Jesus. He also says to his disciples, 'You have not asked for anything in my name: whatever you ask the Father in my name, he will grant you. In fact, the death of Jesus will change the whole state of the relationship between God and man.' That is, because of Jesus' great work on the cross, the disciples and believers will have undeniable and unlimited access to God the Father through him.