building intelligent structure with random evolution requires series of non useful steps
What you say is true, but the answer as to how modern evolutionary theory understand this considers other ideas about living things which seem to allow so called 'neutral traits'.  

Neutral traits being those phenotypes which seem to have no particular relationship to fitness. Toungue rolling is an often mentioned example.  Some folks argue that there is only adaptive changes and phenotype, others like Gould and Lewontin argue that some traits can be the result of pleiotropy.  

So first of all this sort of discussion can tell us that the question is argued both ways in a convincing enough way that it is not resolved in biology - some argue quite confidently that all traits are selected for and things like flagellar motors and upright ambulation and eyeballs evolve because of and experiencing constant evolutionary pressure.  Others argue that these genes that produce these things are doing something else useful while they are becoming these later more useful traits. 

The common twist here is plieotropy.  That the genes that are producing the phenotype one is observing is also participating in one or more other biological traits that may is being positively selected for.  

A more interesting example of how this works is the domesticated silver fox experiment. Foxes which have had domestication bred into them (just to show that it can be done by selection) lose their red color and their ears are softer and fuzzier.  Nobody tried to select for these traits, but they come associated with each fox that is domesticated.  Are these traits plieotropic or only very tightly linked?  So far they have not been exhibited separately.  In any case I think its fair to say that the experiment didn't care about the color of the fox - only its meekness towards people.  These traits come along for the ride. 

So it might be with any other desirable genetic trait.  If a gene becomes closer to producing a lung from a gill, if that gene is sticking around it must be because there is positive selection for that trait, even if the lung like gill is not particularly useful for that fish. 

Sorry but I actually disagree that it is obvious that non-useful steps must be had for any such complicated trait.  If that were true then you would have a point, but not every biologist would give that to you.

It might be a bit surprising that such discussions are and continue to be matters of faith in science, but I hope you don't dismiss it because of this either.  All sciences do assume some things that make their view of the world make more sense.  But there are also other components of these theories which are consistently observed and understood that demand them... until they don't.  

I don't give really any credence whatsoever when someone says 'this is a widely accepted theory by the scientific community'.  This in itself is not a scientific statement, but more the hope that someone else has one somewhere.  But a refutation must also take under consideration what is being refuted.