Only Sinners...
Only sinners are born.
Only sinners come (incarnate) into this material world. Looking down from the spirit world, we see all the activity that goes on and are drawn to certain parts of it. At some point, we decide to investigate or experience what we see and like and plan our descent into that time and place. Our previous incarnations, and the desires we have built up, will to a large extent decide the nature of our incarnation. We can do this alone or with the help of guides. The problem is that when we are incarnated we lose or forget all our past and start over, both mentally and biologically. We do however, bring with us traces or faint recollections of our past. These are locked up deep in our subconcious and influence us through our feelings, emotions, and intuitions.
Only sinners partake of all the sensual delights as well as the pain and sorrow of this physical plane. Matter is basically negative or evil and drags us down over time, and on almost every level. We are limited and weighed upon here with dark thoughts and desires and it is our challenge to overcome these. The material senses give us much pleasure, but they also slowly consume or destroy us. Taste is the lowest or most destructive sense followed by touch, smell, sound, and sight. Eventually we wear ourselves out, age, weaken, and die, and await our next incarnation. It is the principle game here to see how long we can last before burning ourselves out.
Since the material realm is predominantly negative or evil, negativity and evil dominate here, and so do those who are mostly negative or evil. That is why the world and its leaders were, are, and will always basically be corrupt. Given time, material considerations become more important than spiritual ones. Lies win over truth, hate over love, and stupidity triumphs over intelligence. There are exceptions, but not many. We call this darkness or evil Satan or the Devil when it is in fact the very downward and degenerative pull of matter and carnal desire. Very few escape its subtle but powerful clutches. When you do you become a Christed One or Avatar and it then becomes your duty to show others the way out.
The whole point here is that this physical or material realm is the dark or shadow self of spirit. Spirit is experiencing itself from its lowest point so that it can better understand itself. It is a dark and perilous journey for spirit, but one that it needs to grow and develop. We will always be coming back into matter, ever learning new lessons, but our true home is spirit. Thanks to those who are still "unstuck" we are able to return home and someday return the favor. Both the act of coitus and birth are gross and vile and testify to the horrible reality of this plane, yet we still come here, drawn mostly by our lusts and passions. Same for the animals and insects. When there is no longer life on this plane, all will be perfect and at rest.
Source: http://www.librarising.com/spirituality/onlysinners.html