What kind of religion was Christianity when it was founded, and what was its purpose?

Founding: It is the religion of the poor and was founded to safeguard the interests of the poor.

Change: the religion of the poor → the ideological tool of the Roman ruling class → becoming the official religion of Rome (in order to safeguard the interests of the Roman ruling class, consolidate the Roman rule, and strengthen the control of ideas) changed from safeguarding the interests of the poor (the ruled class) to safeguarding the interests of the ruling class.

100% correct.