You need some form of security for your bike. Anything from a big chain & padlock to a remote-control immobiliser.
Disk locks are effective and easily carried with you, its like a dayglo padlock through your front disk.
Chains can be heavy to carry, but mean you can chain your bike to some street furniture or another bike. That makes it much harder to lift your bike into the back of a van.
The best deterrent at home is to keep your bike out of sight. In the garage, or at least under a cover chained to a ground anchor embedded in concrete.