आस्तिकः - नास्तिकः

There is a Panini Sutra "अस्ति नास्ति दिष्टं मतिः" (4-4-60). By this Sutra, we get this form "आस्तिकः" &"नास्तिकः"। This Sutra says "where there is the mind that this is" is known as आस्तिकः। "Where is the mind that this is not" is known as नास्तिकः। Only this much is the actual meaning of these words "आस्तिकः & नास्तिकः"। Now it is up to one's own intellect in what way " this is" & "this is not" are to be interpreted. So you can interpret in many ways such as "there is Veda/God/Deeds/other world" is आस्तिकः। In the same way नास्तिकः could also be interpreted.
However, in ancient days these terms were in use to convey "Veda/God/Other world". In this context Panini coined this Sutra to convey the meaning that were in vogue in those days.
...........