Relics are biblical and no it’s not “ magic “, it is Grace conveyed through physical objects. Paul’s handkerchief and apron for instance.
The Catholic Church has these kinds of relics because of its age.
The science today is stating that The Shroud is authentic and shows the very instant of Christ’s Resurrection, a momentous event for all Christianity. I believe Jesus intended us to have this as a physical record.
If Baptist’s existed from Apostolic times, they too would have relics of The Cross and of many great saints.
The reason they deny relics, is because they don’t have any, and the people that do, they view with prejudice.
Accepting relics would be a validation of Catholics, and we just can’t have that now.
They would rather use these as an opportunity to make another distinctive, than graciously accept the Holy monuments are real and efficacious.