When Allah (swt) created mankind, He (swt) showed him the guidance path. Allah (swt) says:

 {وَهَدَيْنَاهُ النَّجْدَيْنِ }

(And have shown him the two ways?) (Al-Balad: 10)

He (swt) showed him the right and the wrong paths. But what does guidance need? It needs a guide, a person to be guided and a goal to achieve. Therefore, a stray person is the one who strayed from the right course and followed a method other than the method of guidance and walked according to it away from Allah’s (swt) religion.