In this Bhagavad Gita chapter 17 Arjuna inquired from Lord Krishna: O Krishna what is the situation of those who do not follow the principles of scripture but worship according to their awn imagination? Are in goodness, in Passion or in ignorance?  

Men in the mode of Goodness worship the demigods, those in the mode of passion worship the demons, and those in the mode of ignorance worship ghosts and spirits.

In Chapter 16 Krishna explains that there are two kinds of beings one id Divine(Daiva) and Demoniac(Asura). He explains very well the difference between two.  The Supreme Personality of Godhead said: Fearlessness, purification of one's existence, cultivation of spiritual knowledge, charity, self-control, performance of sacrifice, study of vedas , simplicity, nonviolence, austerity, truthfulness, freedom from anger renunciation, tranquillity, aversion to faultfinding, compassion for all living entities freedom from covetousness, gentleness, modesty, steady determination, vigor, forgiveness, fortitude, cleanliness and freedom from envy and from the passion for honor - these transcendental qualities, O son of Bharata, belong to godly men endowed with divine nature.  Pride, arrogance, conceit, anger, harshness and ignorance - these qualities belong to those of demoniac nature.

In chapter 15  of Bhagavad Gita Lord Krishna explains that the splendor of the sun, which dissipates the darkness of this whole world, comes from him. And the splendor of the moon and the  splendor of fire are also from him.  

He enter into each planet, and by his energy they stay in orbit. he become the moon and thereby supply the juice of life to the vegetables.

The Supreme Personality of Godhead said: O son of Pandu. One who does not illumination, attachment and delusion when they are present or long for them when they disappear, who is unwavering and undisturbed through all these reaction of the material qualities, remaining neural and transcendental, knowing that the modes alone are active, who is situated in the self and regards alike happiness and distress, who looks upon a lump of earth, a stone and piece of gold with an equal eye who is equal towards the desirable who is steady equally well in praise and blame, honor and dishonor, who treats alike both friend and enemy, and who has renounced all material activities -  such a person is said have transcended the modes of nature.  

one who engages  in full devotional service, unfailing in all circumstances, at once transcends the modes of material nature and thus comes to the level of Brahman.

Lord Krishna says that the five elements, false ego, intelligence, the unmanifested, the ten senses and the mind, the five sense objects, desire, hatred, happiness, distress, the aggregate, the life symptoms and convictions - all these are considered, in the summery, to be the field of activities and its interactions.   

Humility, pridelessness, nonviolence, tolerance, simplicity, approaching a bona fide spiritual master, cleanliness, steadiness, self-control, renunciation of objects of sens gratification, absence of false ego, the perception of the evil of birth, death, old age and disease, detachment, freedom from entanglement with children, wife home and the rest, even mindedness amid pleasant and unpleasant events, constant and unalloyed devotion to him. Aspiring to live in a solitary place, detachment from general mass of people, accepting the importance of self-realization and philosophical search for the absolute truth all these he declare to be knowledge and besides this whatever there may be is ignorance.

In chapter 12 of Bhagavad Gita,the Supreme Personality of Godhead said: Those who fix their minds in his form and are always  engaged  in worshiping him with great and transcendental faith are considered by him to be most perfect.  

But those who fully worship the unmanifested, that which lies beyond the perception of the senses, the all pervading, inconceivable, unchanging, fixed and immovable - the impersonal conception of the absolute truth - by controlling the various senses and being equally disposed to everyone, such persons, engaged in the welfare of all. at last achieve him.   

For those whose minds are attached to the unmanifested, impersonal feature of the Supreme, advancement is very troublesome. To make progress in that discipline is always difficult for those who are embodied.

In 11th Adhyay of Bhagavad Gita Shri Krishna gave Arjuna the divine vision and showed him his universal form.  

Arjuna saw in that universal form unlimited mouths, unlimited eyes, unlimited wonderful vision. The form was decorated with many celestial ornaments and bore many divine upraised weapon. He wore celestial garlands and garments, and many divine scents were smeared over his body. All was wondrous, brilliant, unlimited, all-expanding.  

if hundred of thousands of sun were to rise at once into the sky, their radiance might resemble the effulgence of  the Supreme Person in that universal form.  At that time Arjuna could see in the universal form of lord the unlimited expansions of the universe situated in one place although divided in to many, many thousands.

In Bhagavad Gita Chapter 10, Krishna says that, neither the hosts of demigods nor the great sages know his origin or opulences, for, in every respect, he is the source of the demigods and sages.  

one who knows him as the unborn, as the beginning less, as the supreme lord of all the worlds - he only, undeluded among men, free from all sins.

In Bhagavad Gita chapter 9 Shri Krishna says that as mighty wind blowing everywhere, rests always in the sky, all created beings rests in him.  Krishna also mention that the all cosmic order is under him. Under his will it is automatically manifested again and again, and under his will it is annihilated at the end.  He also says that nothing can bind him, he is detached from all these material activities, seated as though neural.

In Bhagavad Gita chapter 8 Krishna tell the auspicious time to leave this world(Death). In the light, at an auspicious moment of the day, during the fortnight of the waxing moon, or during the six months when the sun travels in the north.  

The mystic who passes away from this world during the smoke, the night, the fortnight of the waning moon, or the six months when the sun passes to the  south reaches the moon planet but again comes back.  

According to vedic opinion, there are two ways of passing from this world -  one in light and one in darkness. When one passes in the light, he does not come back; but when one passes in the darkness, he returns.