Revivalism

From Wikipedia:

Revival in a Christian context generally refers to a specific period of spiritual renewal in the life of the Church. While elements such as mass conversions and perceived beneficial effects on the moral climate of a given culture may be involved, the key factor in revival is the restoration of the Church to a vital and fervent relationship with God after a period of decline. The word "Church" here refers to the body of believers in Christ as a whole and not to any particular group or denomination among them.