Because, like America, England, and some other countries, China did not like what Germany was doing. they were forcing christianity on people, on jewish men and women, and they didnt like that so they rebeled, and when that happened, they started bombing places making camps to "enslave" in a way, the Jews because they did not accept there religion. in a way, they were the bullies, and America, China, England, and France, did not like that, so they declared war to protect the innocents.
According to the Declaration, ways in which the King denied the colonists "life, liberty and the pursuit of happiness" is that he did not allow them to make their own laws, he did not allow the colonists to trade with other parts of the world and he kept standing armies amongst them in times of peace without their consent.
