Describe the conditions in the roman empire that allowed christianity to grow while the empire itself declined. be detailed

Slaves caused poverty among farmers, who were attracted to Christian salvation through spurning possessions; plagues and war increased desire for salvation and the concept of God's will; Imperial favor toward the Church due to the conversion of Constantine in the 4th Century; and the Catholic Church stepped in for Justinian's Western rule after the Goths conquered the Italian peninsula.

I'm pretty sure it's c. extremely gradual but not 100% sure though.