After 25 years of marriage, and owning the same property throughout that time, is it considered jointly owned even though one spouses name is not on the deed and may one spouse sell said property without the others permission while in the midst of divorce proceedings?

is the properly named in the court action ?

If one party would sell or try to sell, it would have to be at full value and most likely the court would either
1. stop the sell
2. require all funds be put or left into escrow pending court ruling on the home.

In the US the state you live in makes a difference also.

And while the "house" itself may not go to them, they may be awarded large alimony sums or settlement and they use a lien on the home to secure payment

Someone cannot sell a property unless they have title to it.

If the spouse with title does sell it, the divorce court can put the proceeds into the assets to be divided up. Or they can stop or reverse the sale.

Whether the home is considered marital property depends on when it was purchased and what area you live in.