"If you have abandoned one faith, do not abandon all faith. There is always an alternative to the faith we lose. Or is it the same faith under another mask?"

Graham Greene's quote suggests a nuanced exploration of faith and belief. At its core, the quote encourages against the wholesale abandonment of the idea of faith when one specific belief system is no longer viable for an individual. It suggests that faith is diverse and not limited to a single ideology, doctrine, or religion. Therefore, if one abandons a particular faith, it doesn't demand giving up the idea of faith completely.

The idea of "abandoning one faith" acknowledges the individual and often troubled journey of belief. Individuals evolve, circumstances change, and new insights can cause disillusionment or the realization that a certain belief system no longer aligns with individual fact. Rather than seeing this as an end, Greene recommends it offers a chance to explore other types of faith, which may be more unified with one's developing understanding of the world.

The concept that "there is constantly an option to the faith we lose" works as a reassuring pointer of the abundance and diversity of belief systems. It portrays faith as a dynamic and adaptable concept, not restricted to spiritual domains but inclusive of numerous ideologies, philosophies, and personal convictions.

Finally, the rhetorical concern "Or is it the same faith under another mask?" invites reflection on the essence of faith. It implies that while the superficial characteristics of belief systems may alter, they may share core principles or values. Maybe what shifts is not the fundamental tenet of faith itself, but its expression or understanding. Greene recommends that the essence of faith-- trust, hope, or conviction-- may continue under a various guise, and this continuity can provide convenience and guidance.

In essence, Greene encourages an unbiased expedition of faith, advising people to seek and acknowledge their personal facts underneath various kinds and expressions, instead of deserting faith completely when faced with disillusionment.