Well, yes, you can, with small cubes for example, but unfortunately you run the risk of obtaining a kind of cheese purée...
It's quite normal though, with this kind of cheese, unlike Comté for example, the center is very tender, and so is the rind, which is usually eaten (yes, it's a question of taste too).
So with these "soft" cheeses, it's impossible to cut them properly?
Well, normally not, but there's a very simple trick.
The trick is to put the cheese in the freezer for 1 or 2 hours, depending on its size. Say 1 hour for a cheese like camembert or saint-marcellin, and more like 2 hours for a cheese like mont d'or.
At the end of this time, the cheese has hardened, but is not frozen, so it can be cut much more easily.
This is particularly effective if you need to decrust (remove the rind from a cheese), which is normally almost impossible, but after this passage in the cold becomes perfectly feasible.
Be careful not to freeze the cheese completely, as this time it would be almost impossible to cut as it would be too hard.
The best thing to do is put it in the freezer for 1 hour to start with, then come and feel around to see if it has firmed up sufficiently. If not, go back for another 30 minutes or 1 hour, and so on until you reach the right texture.
Once you've finished cutting the cheese, you'll need to let it come back to temperature, unless you're going to cook it afterwards, in which case there's no need.
To sum up: to be able to cut a soft cheese, nothing beats a little time in the freezer to firm it up.