It sounds kind of like the book "Waiting for the Galactic Bus". Two aliens are stranded, one of them gives a primitive hominid a "nudge" towards civilization, and it all goes downhill from there. If so, there is a sequel called "The Snake Oil Wars"
The book is written by Parke Godwin.
The description at Wikipedia:
The tale begins with two college-age brothers, Barion and Coyul, members of an advanced alien world. Their race is endowed with the power to manipulate physical matter with their minds, a power which is exploited incessantly by the young adults. An accident strands the brothers on Earth, which at the time has no human race. The brothers hope for rescue, but eventually grow despondent. In their free time, they cause a series of evolutionary changes in the indigenous primates of Earth, which eventually lead to the blossoming of human civilization.
The brothers grow fond of their project, which they ardently monitor, intervening when necessary. With all the progress they are able to endow humans with, they are never able to rid them of the dim memory of primal darkness, causing a permanent schism between intellect and emotion, which is termed "spiritual schizophrenia". Humans have an insatiable need to decipher the meaning of life, a thirst which leads to stubborn belief systems and immense amounts of violence.
Eons later, the brothers' creation is in danger due to an unlikely courtship. Charity Stovall is a passionately religious young woman from a small American town. She is poised to marry Roy Stride, a violent young fascist. The young couple is oblivious to the fact that if they were to bear a child, it could possibly be more destructive than Hitler to human culture and possibly humanity itself. Subsequently, the two brothers literally put the duo through hell to keep them apart, subjecting them to outrageous scenarios beyond their control.