How does Jesus define the kingdom of God?

After mind becomes man, it has reached a development where memory may be retained, as well as a dim perception of the God Mind from which it sprang.

And strangely enough, it is only then that rebellion against God occurs―

In this transitional state of the soul, it is as if feeling the spiritual quickening before the birth into the true heirship of the sons and daughters of God, the soul were loth to leave its slow, crude condition of mere cosmos force, wherein its odic faculties have lain dormant.

Nothing below man rebels at its appointments. 

And nothing above man, for earthbound spirits are not above him, rebels, but delights and loves to do and discover the will of God.

This is why God so loves the world—so pities it with infinite compassion—when man in that state first struggles with his dim perceptions of good and evil.

This is why He sent his prophets and his Messiah, and why He still sends his Spirits of Light, and will continue to send them until all of mankind is redeemed, that is, becomes fully developed into the perception and joy of being children of God.

There is nothing in all the spheres so gratifying to souls of advanced spirits as being able to minister unto the souls of poor earthbound ones, whether in earthly form—or out of it, and lead them onward toward their glorious heirship into the Kingdom of Heaven. 

You know Christ said The kingdom of heaven is within you.

This is why you should love God, and love to do His will who first loved you—loved you infinitely more with compassion than the most tender mother loves and guides her tottling babe.

This is why you should love your neighbour as yourself to help him and do him no wrong because thus you advance your own soul into that kingdom of love and peace, which is not of earth.

This is why the witness of Christ's divinity is true because of his knowledge of these eternal truths at a time when men on the earth were struggling in greater darkness and ignorance than now. 

And when the spirits of men, freed from their earthly form, yet found few rays of light to lead them.

It is true that He taught no new thing in his commandments, and the substance of the same thought is taught by all prophets of any people―neither can any spirit bring a newer―or truer thought to man than the one incomprehensible, immeasurable thought of God's love to all that He has created, and that you should love Him, and love to do His will that you may grow ever to be more like Him.

As we acquire of his nature, so may we acquire of his knowledge, and thus of his power.

Leaflets of Truth—or Light from the Shadow Land