““The kingdom of heaven is within you.” And concerning the inner man, it consists of nothing but contemplation. Therefore the kingdom of heaven must be contemplation.”

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 269.

Credo (1901)
Context: I believe in the Motherhood of God.
I believe in the Blessed Trinity of Father, Mother and Child.
I believe that God is here, and that we are as near Him now as ever we shall be.
I do not believe He started this world a-going and went away and left it to run by itself.
I believe in the sacredness of the human body, this transient dwelling place of a living soul, And so I deem it the duty of every man and every woman to keep his or her body beautiful through right thinking and right living.
I believe that the love of man for woman, and the love of woman for man is holy; And that this love in all its promptings is as much an emanation of the Divine Spirit as man's love for God, or the most daring hazards of the human mind.
I believe in salvation through economic, social, and spiritual freedom.
I believe John Ruskin, William Morris, Henry Thoreau, Walt Whitman, and Leo Tolstoy to be Prophets of God, who should rank in mental reach and spiritual insight with Elijah, Hosea, Ezekiel, and Isaiah.
I believe that men are inspired to-day as much as ever men were.
I believe we are now living in Eternity as much as ever we shall.
I believe that the best way to prepare for a Future Life is to be kind, live one day at a time, and do the work you can do best, doing it as well as you can.
I believe we should remember the Week-day, to keep it holy.
I believe there is no devil but fear.
I believe that no one can harm you but yourself.
I believe in my own divinity — and yours.
I believe that we are all sons of God, and it doth not yet appear what we shall be.
I believe the only way we can reach the Kingdom of Heaven is to have the Kingdom of Heaven in our hearts.
I believe in every man minding his own business.
I believe in sunshine, fresh air, friendship, calm sleep, beautiful thoughts.
I believe in the paradox of success through failure.
I believe in the purifying process of sorrow, and I believe that death is a manifestation of life.
I believe the Universe is planned for good.
I believe it is possible that I shall make other creeds, and change this one, or add to it, from time to time, as new light may come to me.

Vol. I, The Way of Illumination Section I - The Way of Illumination, Part III : The Sufi http://wahiduddin.net/mv2/I/I_I_3.htm
The Spiritual Message of Hazrat Inayat Khan
Context: What is the Sufi's belief regarding the coming of a World Teacher, or, as some speak if it, the "Second Coming of Christ?" The Sufi is free from beliefs and disbeliefs, and yet gives every liberty to people to have their own opinion. There is no doubt that if an individual or a multitude believe that a teacher or a reformer will come, he will surely come to them. Similarly, in the case of those who do not believe that any teacher or reformer will come, to them he will not come. To those who expect the Teacher to be a man, a man will bring the message; to those who expect the Teacher to be a woman, a woman must deliver it. To those who call on God, God comes. To those who knock at the door of Satan, Satan answers. There is an answer to every call. To a Sufi the Teacher is never absent, whether he comes in one form or in a thousand forms he is always one to him, and the same One he recognizes to be in all, and all Teachers he sees in his one Teacher alone. For a Sufi, the self within, the self without, the kingdom of the earth, the kingdom of heaven, the whole being is his teacher, and his every moment is engaged in acquiring knowledge. For some, the Teacher has already come and gone, for others the Teacher may still come, but for a Sufi the Teacher has always been and will remain with him forever.

Chapter 11 The Textbook of Love http://www.unification.net/truelove/tl1-11.html 1984-02-05

1920s, Process and Reality: An Essay in Cosmology (1929)

Source: The Light of Day (1900), Ch. III: Science and Theology

"The Indifference of Heaven"
Mutineer (1995)

Introduction, Z. Hanfi, trans., in The Fiery Brook (1972), pp. 101-102
The Essence of Christianity (1841)

Source: Heaven Revealed (Moody, 2011), p. 27