The Cappadocian Church Fathers teach that God first creates the world and beautifies it like a palace, and then leads humanity into it. The genesis of the cosmos, is a mystery (mysterion) for the human mind, a genesis produced by the Word of God. As such, the world is a revelation of God (Rom. 1:19-20). Thus, when its intelligent inhabitants see it as cosmos, they come to learn about the Divine wisdom and the Divine energies. The cosmos is a coherent whole, a created synthesis, because all its elements are united and interrelated in time and space. A serious study of the mystery of creation, through faith, prayer, meditation and science, can help one see and appreciate the the integrity of creation.

St. Basil the Great said:

"We should understand in the creation the original cause of the Father as a founding cause, the cause of the Son as a creative, and the cause of the Spirit as an implementing one." Thus the Father is the "Creator of all things", the Son is the one "through whom all things were made", and the Holy Spirit is the one "in whom are all things". “Everything that He (God the Creator) had made ...was very good" (Gen. 1:31), because "first He conceived, and His conception was a work carried out by His Word, and perfectly by His Spirit.”

Creation is the action of the Son bringing God the Father’s desire into existence and the Holy Spirit perfecting it in goodness and beauty; the one calling the creation and leading it to the Father, and the other helping the creation to respond to His call and communicating perfection to it. Thus, the creation is the result of the close relationship and cooperation of the Holy Trinity. The community of three Persons participates actively in the execution of the whole of God's plan.

The created world is distinct in essence from God. The world was brought into being out of non-being and not created out of an eternally existing material. Beholding the heavens and the earth, and seeing all that is there, you will understand that God has created it all from nothing (2 Macc. 7:28).

As St. Gregory of Nyssa affirms:

"It begins to be, and the very substance of the creation owes its beginning to change". This transition from non-existence is a change brought about by God's creative Word "who has established the world so that it shall not be moved" (Ps. 93:1).

The world did not form itself, but is dependent on the will of God. The world is a production of God's free will, goodness, wisdom, love and omnipotence. God did not create out of necessity. God created so that other beings, glorifying Him, might be participants in His goodness. 
The account of Creation in Genesis clearly shows us that the world does not exist eternally, but has appeared in time. Further, it did not appear in a single instant, but was created in sequence.

Saint Gregory the Theologian says:

“There is a certain firstness, secondness, thirdness, and so on to the seventh day of rest from works, and by these days is divided all that is created, being brought into order by unutterable laws, but not produced in an instant, by the Almighty Word, for Whom to think or to speak means already to perform the deed. If man appeared in the world last, honored by the handiwork and image of God, this is not in the least surprising; since for him , as for a king, the royal dwelling had to be prepared and only then was the king to be led in, accompanied by all creatures.”

“The world was not conceived by chance and without reason, but for an useful end and for the great advantage of all beings, it is really the school where reasonable souls exercise themselves, the training ground where they learn to know God; by sight of visible and sensible things the mind is led, as by a hand, to the contemplation of invisible things.”

Saint Gregory of Nyssa writes,

“Scripture shows the vital forces blended with the world of matter according to a gradation: first, it infused itself into insensate nature; then advanced into the sentient world; then ascended to intelligent and rational beings.... The creation of man is related to coming last, who took up into himself every single form of life, both that of plants and that which is seen in animals. ...what is perfect comes last, according to a certain necessary sequence in the order of things... 
Thus we may suppose that nature makes an ascent as it were by steps--I mean the various properties of life--from the lower to the perfect form.”