It is on account of the ego that one is not able to see God. In front of the door of God's mansion lies the stump of ego. One cannot enter the mansion without jumping over the stump.
So long as the bee is outside the petals of the lily, and has not tasted the sweetness of its honey, it hovers around the flower emitting the buzzing sound; but when it is inside the flower, it noiselessly drinks the nectar. So long as a man quarrels and disputes about doctrines and dogmas, he has not tasted the nectar of true faith; when he has tasted it, he becomes quiet and full of peace.
Imagine a limitless expanse of water: above and below, before and behind, right and left, everywhere there is water. In that water is placed a jar filled with water. There is water inside the jar and water outside, but the jar is still there. The 'I' is the jar.
To work without attachment is to work without the expectation of reward or fear of any punishment in this world or the next. Work so done is a means to the end, and God is the end.
It is true that God is even in the tiger, but we must not go and face the animal. So it is true that God dwells even in the most wicked, but it is not meet that we should associate with the wicked.
You speak of doing good to the world. Is the world such a small thing? And who are you, pray, to do good to the world? First realise God, see Him by means of spiritual discipline. If He imparts power you can do good to others; otherwise not.
Only two kinds of people can attain self-knowledge: those who are not encumbered at all with learning, that is to say, whose minds are not over-crowded with thoughts borrowed from others; and those who, after studying all the scriptures and sciences, have come to realise that they know nothing.
If you first fortify yourself with the true knowledge of the Universal Self, and then live in the midst of wealth and worldliness, surely they will in no way affect you.