Romans 6:5

For is we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection.  

The goal of God was never to get us saved only and remain at that level.  Salvation was just the start of our world overcoming power through faith in Jesus Christ.  The apostles grew in faith and accomplished many miracles after the death of Jesus on the cross.  They are our example, along with Jesus, for what our lives can be on this earth.