Why do you think the last sentence of the Declaration of Independence was written?

I need help answering this question for my government class. I really don't know what the last sentence means so it's hard for me to answer the question.

The last sentence of the Declaration is... " And for the support of this Declaration, with a firm reliance on the protection of divine Providence, we mutually pledge each other our Lives, our Fourtunes and our sacred Honor."

Any help is appreciated! Thank You!