My Kingdom
And greater works than these shall ye do, because I go unto My Father.
While I was on earth, to the great number of those with whom I came in contact, Mine was a lost cause. Even My disciples only believed, half-doubting, half-wondering. When they all forsook Me and fled it was not so much fear of My enemies as the certainty that My Mission, however beautiful they thought it, had failed.
In spite of all I had taught them, in spite of the revelation of the Last Supper, they had secretly felt sure that when the final moment came, and the hatred of the Pharisees was declared against Me I should sound some call to action, and that I should lead My many followers, and found My earthly kingdom. Even the disciples who had eyes to see My Spiritual Kingdom had thought material forces had proved too strong for Me.
But with My Resurrection came hope. Faith revived. They would remind each other of all I had said. They would have the assurance of My Divinity, Messiahship, the lack of which had hindered My work on earth, and they would have all My Power in the unseen - the Holy Spirit - to help them.
Remember, I came to found a Kingdom - the Kingdom.  Those who lived in the Kingdom were to do the work -- greater works than I was able to do. Not a greater Power shown, not a greater Life lived, but, as men recognized My Godhead, opportunities for works in My Name would increase. My work on earth was to gather around Me the nucleus of My Kingdom, and to teach the Truths of My Kingdom to them.  In those Truths they were to live and work.
"But now it is Christ risen from the dead, and become the first fruits of them that slept. For since by man came death, by man came also the Resurrection of the dead." 1 Corinthians 15:20-21

Blessed Assurance
And the work of righteousness shall be peace; and the effect of righteousness quietness and assurance for ever.
-- Isaiah 32:17.
Be still and know that I am God. Only when a soul attains this calm can there be true work done, and mind and soul and body be strong to conquer and to bear.
The Peace is the work of righteousness -- living the right life, living with Me. Quietness and assurance follow.
Assurance is the calm born of a deep certainty in Me, in My Promise, in My Power to save and keep. Gain this calm, and at all costs keep this calm. Rest in Me. Live in Me. Calm, quiet, assured -- at Peace.
Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, ... Grace unto you, and peace, be multiplied. 1 Peter 1:2