The dispute over qualification can sometimes be verbal: both parties affirm present faith but understand the phrase “God willing” differently. It becomes substantive if one view actually permits doubt about basic present assent while the other requires certainty.
The concluding distinctions are four: present faith, its perfection, future perseverance, and ultimate outcome.
Keeping them separate clarifies the relation of Islam to faith, the role of outward profession, the different explanations of qualification, and the fact that a created person's condition may change without change in the divine attributes.