Thoughts about Judaism.

I was having lunch with a friend today, and I discussed how I did not fast on Tisha B'Av. I told her I did not fast for several reasons:

1. I only even found out about the holiday during my first year of law school, when I was told during my first meeting with the Jewish Law Students Association to write to the Board of Bar Examiners, because the July bar was scheduled during Tisha B'av. I had no idea what that entailed at the time. I found out more details concerning this holiday only after reading Jews, God, and History by Max Dimont, but in short...it is not something I grew up with and is a part of me.
2. I am not sure if the destruction of the temple is a bad thing. I know that the destruction of the first and second temples meant massive death, as well as the Jewish Diaspora and statelessness, HOWEVER, it also brought a rich Jewish legal tradition and the end to the 'cult of the temple.' The Sadducees had a Judaism ruled by ritual more than personal faith. They did whatever the high priest told them to do, and did not have any rich body of interpretive law. It was a religion with animal sacrifice as well as laws such as death for apostacy and homosexuality. This was not a Judaism that I would be proud of, or even relate to. And this is the Judaism that would return, at least theologically if a temple were to return. Is this something to aspire to? Again, I am not saying I am happy about the massive Jewish death that went along with the destruction of the temples (I want to reiterate that this remains a horrible tragedy); I just am wondering if the destruction of the temples was a good thing for the intellectual development of Judaism.
3. This brings me to point three. I told my friend that Judaism holds the temple can only be rebuilt if the messiah comes. Christianity holds that the end of days is nigh when the temple is rebuilt. I posited the following to her...what if the temple is rebuilt, and there is no messiah? Does this not completely undercut the very foundations of Judaism and Christianity? How can you be a believing Jew or Christian when one of the central tenets of your faith was just literally disproven in front of your eyes? My friend looked at me in wonderment; she is a Jain, and her 'religion' is actually more of a philosophy and way of life than it is a 'religion.' It cannot be outright disproven in the way that the 'big three' monotheistic faiths literally can be. But that got me thinking on a much deeper level...my friend never really understood the theology behind the messiah and end of days, and I described it to her as best I could. I described to her that Christians believe the end of days will happen when the Jews rebuild the holy temple, and I believe 144,000 saved Jewish people as well as all born again Christians will rise to the Kingdom of Heaven. Jews believe that the messiah coming means there will be a time of increased spirituality on earth or peace, love, and prosperity. Everyone will know the true meaning of Hashem's love. Eventually, Hashem will bring the dead back to earth, and heaven and earth will become indistinct.
   
   While I said that...I thought to myself..."Not only do I not believe this, but I sound like a crazy person saying it!"
4. What does it mean to be a Jew if you really have felt a spiritual presence and do think there is a divine energy in the universe, but do not believe in the messiah, one of Maimonedes's 13 Principles of Faith? Not only do I not believe, I see it as an outright fairy tale; in short, it is a positive lack of belief in this, rather than a simple apathy.
   
   If I really believe that a core tenet of Judaism can be disproven on earth...how does that impact the rest of Judaism?