How we cite our quotes:
MANDERS. It is the very mark of the spirit of rebellion to crave for happiness in this life. What right have we human beings to happiness? We have simply to do our duty, Mrs. Alving! And your duty was to hold firmly to the man you had once chosen, and to whom you were bound by the holiest ties. (1.358)
In a nutshell we have Manders's philosophy. The emphasis on duty and self-denial stands in stark contrast to Oswald's later explanation of the joy of life.
MANDERS. But a wife is not appointed to be her husband's judge. It was your duty to bear with humility the cross which a Higher Power had, in its wisdom, laid upon you. (1.360)
While he acknowledges the possibility that Captain Alving wasn't what he seemed, Manders doesn't think it matters. His religion tells him that suffering is not only appropriate, it's an honor.
MANDERS. You have never known how to endure any bond. (1.370)
Manders accuses Mrs. Alving of narcissism and self-interest. That may be part of the story, but the other part is the endurance of the bond to her son, for whom she has sacrificed her happiness.