Thanks for your question.
The term you used, Millenialism, refers to the millenial reign of Christ and the saints following the return of Christ to the earth.
Here are some links to items in the website on this subject:
Millenium means a period of 1,000 years. In Revelation chapter 20 this time period is mentioned 6 times in relation to the reign of Christ on earth.
God bless,
Mike