Moral of Joshua 7: Make sure your family does not sin or else you will be punished for their sins!

In  my journey throughout the Bible, I have reached Joshua. Throughout my readings, I have found many many inconsistencies of what the bible says is appropriate behaviour and how to treat others. However, I have found things that have reassured me. I grew up in a Christian household where  the ideals and sayings from the Bible are often told as morals. About mid-Exodus, I was becoming very discouraged that I would ever finish with my goal to read all the of the Bible. I had grown up hearing about this great God who saved people and tried to do his best at making everyone safe and provide for them everlasting life. Through my readings of the Bible thus far, I found that this God did not exist. This god was jealous, lost his temper easily, and often went back on his word. However, I found the passage that says that one shall not be judged for the sins of the father (or any family member). This was very reassuring for me because I definitely do not want to be judged because of some of my crazy relatives! Everyone has those crazy relatives that you only claim as relatives at family reunions just because your mom makes you! Deuteronomy 25:16 says "The fathers shall not be put to death for the children, neither shall the children be put to death for the fathers: every man shall be put to death for his own sin.". As I continued my readings of the Bible and of the Good Book, I finally finished with Exodus and started with Joshua. In Joshua, I came upon the story of the battle of Ai. This story made sense until I reached the part about the thief's family being killed for his actions. This goes completely against what God and the Bible had earlier stated about the sins of the father! How is this fair that one person does the wrong thing but an entire family is punished for it?!? It is not fair, right, or just, which are three of the various titles that God claims for himself. This single passage has managed to make me question why the Bible has been revered as a spiritual book for the last couple thousand of years. I completely see the literary value of the book but am losing sight of the spiritual value. In the past few weeks, we have often discussed how the morals of Biblical stories are very ambiguous if they exist at all, God is a fickle being, and the Israelites are complete idiots in the way they behave! Why do we look up to this book and to this group of people for guidance. In the first few books of the Bible, the Israelite's are often told not to do horrible things, which leads me to think that they are committing these atrocious acts! Why tell someone not to do something if they are not already doing it?
The literary value of the Bible is implicitly clear in every page that one reads whether it has been written by the J or P writer. Every page helps set the stage for future writers by giving them examples of correct procedures to set up repetitive parallel or how to tell an awesome story. I always thought that reading the Bible in its entirety would help me with my spiritual understanding but instead it is strengthening my literary understanding since every piece of literature owes at least a piece of its existence to the Bible.