A lady in a white religious gown is being questioned by many people as she walks.
nobody seen her when the angel came on earth
An angel does not imply a lady, or vice versa. Many people is more than nobody.
A lady wearing a white religious gown is not an angel. If a lady is being questioned by many people, then it cannot be claimed that nobody has seen her. If a lady came on earth, then is is unlikely that she walked to get there.
The subject cannot be a lady and referred to as nobody simultaneously.