How can I combat condensation in my home without opening the windows?

Get a dehumidifier. And make sure less water vapour gets inside in the first place (keep the window open and the door shut when you have a shower, dry clothes outside or in the dryer etc).

Stop drying your washing in the house but when ever there is heat even a little in a house the heat hitting a cold surface like walls and windows will produce condensation as will cooking and even breathing as your breath is full of moisture

Not 100% sure this will work so I would suggest trying it on a small window first if you choose to try it at all. You know when you are in the shower and the mirror fogs up? If you clean if with shaving cream/gel it prevents it for a while. It may work for condensation on windows too but I could be wrong.

A small dehumidifier would be best but only use with windows and door shut or it draws moisture from outside.

Fit an Extractor in the outside wall.

higher furnace temperature ,or better insulation in the walls

put a glass of water by the fire-place, it works for me

you have two choices open a window or door ...or stop breathing ...