Can a Protestant be unregenerate while claiming to be regenerated?

Lutero:

Is it possible that by refraining from many sins
diligently frequenting church and participating in sacraments,
that Roman Catholics can still be in SIN,
pretending to be regenerated without being so?

Can a Catholic be engaged in sin, while not being in a state of sin?

Is it possible that while claiming to be saved by faith alone and
diligently proclaiming the grace of God in front of many others,
that Protestants can still be in SIN, pretending to be regenerated without being so?

Can a Protestant be unregenerate while claiming to be regenerated?

Sincerely,

De Maria