There is a term “自然法爾” (Shizen Houni). It means we possess innate worth naturally. This worthy thing is called “仏性” (Buddha nature). All plants and animals, flora and fauna possess inborn worth inside of them. It has potential that become like a diamond. That means we all can become a buddha (a buddha is a person who enlightened) because we have a buddha nature that is a core of our spirit and soul within. However, it doesn’t means that everyone can become a buddha if you don’t do discipline and polish a diamond otherwise it stays as a coal. We are equally given such a precious potential, because we are so worthy as children of God, but it is necessary to do discipline for making it as a diamond.
一切衆生悉有仏性 vs. 一切衆生悉皆成仏
一切衆生悉有仏性 (issai syujjou shitsuu bussho) is that all living things have the possibility of becoming a buddha who is a enlightened person although still there is an idea of 断善根 (danzenkon) means that someone doesn’t have a buddha nature and disconnected with Buddha so he or she cannot become a buddha. 一切衆生悉皆成仏 (issai shujou shikkai joubutsu) means everyone can become a buddha. This is true, we all have a possibility to become a buddha because we all have a buddha nature. However, it doesn’t mean that we all become a buddha without discipline or just after we die. In some sect of Buddhism, we say “he became a buddha” at funeral. But it is not easy. To become a buddha requires so much efforts throughout so many reincarnation. There are so many steps for that path.
This idea that we all possess Buddha nature requires to make us efforts to shine it throughout so many lives. It is very different from idea that if you believe in God you will be saved.