What are the Dangers of Bid'ah

Bid'ah implies falsely accusing the Messenger of Allah ﷺ. It's as though this innovator is saying that the Prophet ﷺ did not complete the religion or the shari'ah (legislation), because there is (some parts of the) religion and shari'ah which he did not come with. Then, there is another very great danger in bid'ah which is that it indicates disbelief in the saying of Allah (the meaning of which): "This day, I have perfected your religion for you." That's because when Allah the Exalted completed the religion, it means that there is no (other addition to the) religion to what the Prophet ﷺ has come with. These innovators legislate in the religion of Allah what is not from it, from saying Subhan Allah, La ilaha illa Allah, some movements, and other things. They in reality don't believe in the saying of Allah (it's meaning): {This day, I have perfected your religion for you.}