Prophet Muhammad(SAWS) never ridiculed other religions and his spreading of the messages of Islam was always imbued in kindness through his speech and actions.
In his plight to create a peaceful spread of Islam, Prophet Muhammad had his followers enact a document to regulate the relationship between people of the Book around Madinah, where Islam was a growing civilization.  According to the sources, this is what the document said:

“Whoever joins the signatories of this scripture would be entitled to our help and would not be subject to any injustice, nor should the Muslims cooperate against them. The children of Ouf (a Jewish tribe) are community of believers. The people of the scriptures are allowed to follow their religion as much as the Muslims are allowed to follow theirs, and so are their allies except the one who commits injustice or sin, for he does not harm but himself… The signatories of the document are entitled to mutual advice, sincerity and assistance rather than fighting each other…” (503)

This document was the first in history establishing religious pluralism and freedom of beliefs. Peace was enacted as long as everyone celebrated the goodness of their religions and did not impose their beliefs on others.