It depends
If you have previously collected data that is personalised e.g name, religion then yes
To quote the legal authority in England that will enforce this legislation
The GDPR applies to ‘personal data’ meaning any information relating to an identifiable person who can be directly or indirectly identified in particular by reference to an identifier.
This definition provides for a wide range of personal identifiers to constitute personal data, including name, identification number, location data or online identifier, reflecting changes in technology and the way organisations collect information about people.
The GDPR applies to both automated personal data and to manual filing systems where personal data are accessible according to specific criteria. This could include chronologically ordered sets of manual records containing personal data.