The chances of a primordial sludge bringing about complex cells, given that it is possible, is actually quite good if you look at the sheer number of trials.
First off Millers experiment, an attempt to reproduce conditions during the earths cooling and see if life could form from inorganic material, while not proving that life on earth actually emerged from such conditions, did prove that at least basic building blocks of life could be crated from raw materials and energy.
Now let’s say the conditions necessary to form proteins, or amino acid, or other such basic parts(I’m going to refer to these as BPs from now on) of cells only happen 1000 times a second world wide (given that these conditions are only a random gathering of chemicals and energy in some form, and on rather small levels of each I’m assuming this is a very conservative estimate) and that the chances of these conditions actually forming a BP is very small for calculations sake lets say 1 in a billion and lets also say that the chance of these BPs forming cell is very very small lets say 1 in a trillion and lets also say that the chances of this life form actually very very very small (technical term : P) 1 in a trillion in a trillion or 1 in 1,000,000,000,000,000,000,000,000 this give the chance of life that will continue on our primordial earth at any given second a 1 in 10^42 chance of forming. Very slim by any regards.
But now onto # of trials given that there are 31.5 million seconds a year (rounded) and that this forming of life could have happened over a time of say 4 billion years. Gives our planet a
1 in 8,000,000,000,000,000,000,000,000 chance of forming life.
Still very small.
But what I am trying to prove is not that is likely that simply our planet could form life but any planet COULD make a form of life. The reason that I say form of life is that I am not limiting all life to our cellular structure, basic need for water and oxygen, and even chemical makeup. If a life form does not have to meet our criteria then ANY planet or large object close to a source of energy (a star) could meet the requirements. Given that there are 1,000,000,000,000,000,000,000 stars in universe (NASA estimate) and assuming that each star only has 1 such large objects (for purposes of simplicity, as some have many large objects and many stars have none.) now the chances of some kind of life is only 1 in 8. Adding a zero here or there will dramatically change this number.
Now I’m not even close to suggesting that any of my numbers unless otherwise stated are correct, I’m merely trying to illustrate the point that even if the chances of life are extremely small in any given place, when taking a view of a large enough scope, the zeros will eventually stack in the favor of life, and it is only because we exist within this statistical anomaly that creationists are able to say its not by chance but divine will, truly the numbers are so stacked against us ( as in 1 : 10^42) that only a deity of supreme power could make it happen. What I I’m saying is that simply because something is very unlikely to happen in any given instance, it is still statistically likely to happen given enough trials.