What science is and why religion gets no credit for the Big Bang.

Science is a process of making models to describe the world less and less wrong. What explained 99.5% of the data is fixed and expanded to explain 99.9% of the data and then 99.99% of the data. The best a good theory can do is explain 100% of the current data we have available which is why when we find an exception and something that isn't explained by the theory we finally have an opportunity to expand and refine our theory and make it less wrong. The truth of an idea, not only, must be conducted by explaining all of the current data but all of the future data as well. If you get distinct and new data that fits perfectly into the current theory or data that is predicted as an expansion of the theory... that's good science.

Did science accept the steady state universe just to destroy God? Wasn't that a step backwards?

When science accepted a steady state universe there were good reasons to accept this. There was no data to suggest that the universe had a beginning. In fact the considerable amount of evidence seemed to firmly support the unchangingness of the heavens as observed by Aristotle in his book On the Heavens. This was first refined when one of the later Aristotelian thinkers observed what was probably a supernova that showed that the unchangingness of the aether was false and we should start writing down what the sky is doing and looks like. From the origins of science the observations were firmly on the side of the universe being largely unchanged and immutable. The Big Bang only became an acceptable theory in the 1960s with the discovery of the CMBR.

There are real examples of stepping backwards.

One need look no further than Copernicus the first of the modern heliocentrists who wrongly insisted that the planets traveled at constant speed and distance from the sun. This oversight lead to heliocentrism stagnating as Ptolemy's towering genius laid out a way of figuring the epicycles (the little bits where the planets seem to go backwards because the earth passes them in orbit) of the planets and this model can give exact locations of the planets at anytime. Whereas Copernicus for being right, stripped out the varying speeds and ended up with a system that couldn't properly calculate the position of the planets. The Copernican system was largely inexact and didn't work very well until Kepler restored the Ptolemy assumption of varying speeds. Which after Newton invented calculus (precisely to solve this problem) made the heliocentric model simpler and more able to do the same precision of calculations as Ptolemy could.

Though placing the sun at the center was certainly more correct, it didn't explain more of the data, it did create a much simpler model. However this simply lead to hybrid models where heliocentric models were used in theory and Ptolemy was invoked when calculations needed to be done.

However, the end result is that science progresses. Even if it needs to go through ebbs and flows. At no point did we accept the worse calculations while tangentially accepting the better theory (at least after Galileo). However, it was not a scientific belief that the universe had an origin from the dawn of science. The data we had were of a universe that didn't seem to vary much at all. It wasn't until we started seeing different stuff in the distant parts of the universe (and thus in the distant past) that were different, detected the red shifted hiss of the big bang, and observed as the universe flung apart that we accepted the theory.

As there are only two possible considerations that the universe began or the universe didn't, there isn't much credit to be given to having picked one on the basis of no evidence. The history of science has always been that of an unchanging universe. Similarly that seems the thrust of most religious thoughts as well. God made the universe one day, just as it is today. There's a pretty considerable difference between the theology of creation and the science of the Big Bang. In fact, I've seen a number of Bible Believing Christians attack the Big Bang theory precisely because of these differences.