OK, first let's estimate how much force you'd need.
Let's start with the mass. The temple should be made of stone, you say. The lightest stone as far as I know is Pumice. The stone in the image on the Wikipedia page has, according to the caption, a density of $0.25~\mathrm{g}/\mathrm{cm}^3$. Since I can't fine a more general statement about the density (apart from "it floats on water") I'll assume that this is a typical density, and use it in the following calculations.
Unfortunately I cannot find much about the other properties, so I can only guess on how thick the walls would have to be. I'll assume 25 cm, which is a normal thickness for an outer wall. I have no idea what a normal thickness for the roof would be, so I'll assume the same there; the floor plate (the "land") should probably be twice as thick to carry the load. But note that this is just a guess. I'll just calculate with a flat roof, although the temple will probably have a non-flat roof.
So putting all the numbers in, I get:
- 1 roof: $600~\mathrm{cm}\times 1200\mathrm{cm}\times 25\mathrm{cm}\times 0.25 \mathrm{g}/\mathrm{cm}^3 = 4500~\rm kg$
- 2 long walls, each half as high as the roof is wide: $4500~\rm kg$
- 2 short walls, each half as long as the long walls: $2250~\rm kg$
- 1 floor: twice as thick as the roof, $9000~\rm kg$
- 50 people, $77~\rm kg$ each: $38500 kg$
- You'll probably also want to put some stuff into the temple; let's add another $900~\rm kg$ for it.
So the total mass of the temple including people is about $25000~\rm kg$. Assuming earth-like gravitation (i.e. $g=9.81~\mathrm m/\mathrm s^2$), this gives a force of about $245~\rm kN$; let's round it up to $250~\rm kN$ for easier calculation (that then allows also for a more fancy roof).
Now the density of air is $1.225~\mathrm{kg}/{m}^3$, so the lower bound of the volume you'd need to get enough buoyancy (namely, if you could just use pressured vacuum, which of course doesn't exist) would be about $204\,000~\mathrm m^3$. For comparison, your temple itself has a volume of $216~\mathrm m^3$. So you'd need about 244 times the volume of your temple to create enough buoyancy (in reality more since even the lightest gas is considerably heavier than the imaginary pressured vacuum, and thus provides less buoyancy).
So unless you could live with a gigantic balloon on top of your temple, buoyancy is out of the question, even if you manage to get the mass down to a tenth of what I calculated.
So what else could we use to create the gigantic force? Well the strongest force in the universe is the electromagnetic one. So let's see if we can do with that.
The first idea would be that the floor and the temple contain electric charges, so they repell each other. You'd need to perfectly insulate both charges (especially the one in the floor) so they don't simply flow away. Now, how much charge would you need?
Let's for simplicity assume that the charges of the temple and the floor are both contained in giant plates, one in the floor below the temple, and one in the floor of the temple. Let's als assume that the charges are of the same magnitude. The formula for the force is then $F = Q^2/(2 A\epsilon_0)$ where $Q$ is the charge, $A$ is the area of the plate, and $\epsilon_0 = 8.85\cdot 10^{-12}~\rm As/(Vm) = 8.85\cdot 10^{-12}~\rm C^2/(Nm^2)$. Solving for the charge gives $Q = \sqrt{2 A \epsilon_0 F}$, and inserting $A = 6~\mathrm m\times 12~\mathrm m = 72~\mathrm m^2$ and $F=250~\rm kN$, we get $Q = 0.017~\rm C$. Now that doesn't sound much, but when you calculate the field strength that results, you find that it is $14.7~\rm mV/m$, which is almost five times the breakdown field strength of air (that is, the voltage at which you get lightning/electric arcs). So again, that's not a good solution (I certainly wouldn't enter that temple!)
So what remains is magnetic forces. Unfortunately I don't know how to assess if this would give a reasonable force without unreasonable assumptions.
