Christianity is a tricky subject to a lot of people and as I do believe that the old testament should be just as important as the new testament you have to understand that a lot of the old testament laws have to be clarified. What you read if you are offended is probably not an accurate translation and if it is you need to compare it to what was going on in the area at the time. For example when the people are told in the old testament not to eat pork. Disease was spreading rampantly back then so it was necessary to apply that law.
As far as the difference between the Christians that worship basically through the new testament that's fine by me. It takes extra time and effort to really get the meat from the old testament and see what's going on at the time. The new testament is more relatable for people and although Christ did establish a new way to approach God the old way was just as viable, just changed. Not into something new but altered in a way that what was complicated but it now somewhat streamlined. It's not easier, it's just different. When you're reading the bible you can't look at it as the old and new testaments, you have to look at it as one continuous book. Seperating them only gives you half the story.