John Wilkins has written a FAQ on the probability of abiogenesis.
What Louis Pasteur and the others who denied spontaneous generation demonstrated is that life does not currently spontaneously arise in complex form from nonlife in nature; he did not demonstrate the impossibility of life arising in simple form from nonlife by way of a long and propitious series of chemical steps/selections. In particular, they did not show that life cannot arise once, and then evolve. Neither Pasteur, nor any other post-Darwin researcher in this field, denied the age of the earth or the fact of evolution.
From the early views of Aristotle, through the research by Louis Pasteur to abiogenesis research, Wilkins shows how these fascinating concepts evolved.
A worthy addition to the Probability of Abiogenesis FAQs