Going from OT to NT is interesting. At mass you get an old testament reading, a new testament reading, and a Gospel reading. Followed by a sermon that explains the readings, how they all relate, and what it means to us in our lives. Often the old testament reading prophesies what's fulfilled in the new testament.

That's the general theme, the OT is the promise and NT the fulfillment so they cannot be at odds. If you consider the the OT was written to teach moral truths, not history, not "The Art of War" and was written to address the people of the times much can be reconciled. The Jewish patriarchy was particularly strong (ferinstance "father" was all-controlling and could be translated as "lord," call no man lord) and rulers were cruel and absolute

The key elements in human thinking are not numbers but labels of fuzzy sets. -- L. Zadeh

Which explains a lot.