There is a way to get God Mode by editing the config.cfg file and changing the following entry:

cfg_SPPlayerDamageModifier = 0.35
to this:
cfg_SPPlayerDamageModifier = 0.00

Note that this will only work in the Campaign mode, and remember to make a backup of the file in case you don't want to be in God Mode any more.

When doing this ships under your command will not take any hull/shield damage.