"For ever and ever" is a biblical expression used to emphasize the infinite duration of something. However, there are several synonyms that can be used to convey the same meaning. Some of these include "eternally," "perpetually," "endlessly," "forevermore," "unceasingly," "indefinitely," "infinity," and "everlastingly." These synonyms emphasize the idea of something without an end, something that will always be present or something that will never cease to exist. Whether you're talking about love, devotion, or loyalty, using any of these synonyms would add depth and emphasis to your expression.