God did not create the evil. He established the laws which are always good because he is good. The spirits would have been completely happy had they faithfully observed the law since the beginning. But, being free to make choices, the spirits have not properly obeyed them so that evil come as a consequence of this unwillingness. One can then say that good corresponds to everything which is in accordance with God's law while evil is everything which opposes it.
Prayer is always acceptable to God when dictated by the heart, for the intention is everything in his sight; and the prayer of the heart is preferable to one read from a book, however beautiful it may be, if read with the lips rather than with the thought.
In order to cooperate in the material worlds as agents of a divine power, the spirits temporarily have a material body. By the work required in their corporeal lives, the spirits improve their intelligence and, by observing God's law, they acquire the merits which will lead them to eternal happiness.