Firstly, what is secular? Is there a formal definition of secular? Oxford dictionary defines secular as:

A. adj. I. Of or pertaining to the world.
a. Of members of the clergy: Living ‘in the world’ and not in monastic seclusion, as distinguished from ‘regular’ and ‘religious’.
b. Of or pertaining to secular clergy.
2. a. Belonging to the world and its affairs as distinguished from the church and religion; civil, lay, temporal. Chiefly used as a negative term, with the meaning non-ecclesiastical, non-religious, or non-sacred.

Yes. Shivaji was not secular by any means. so are today’s politicians (at least in India!). Secular does not mean equality to religions. Secular person is one who is isolate from any religion.

Now regarding 500 Pathans!

He certainly employed several Muslims, who served him with loyalty. The numbers are not important nor whether they were spied or not. Perhaps some other Hindu soldiers were spied as well. In fact, Shivaji clearly knew the importance of the loyalty of his cadre. I think in the discussion, what is important is that he respected other religions. He never questioned religious beliefs of his enemy either and always paid respect to the killed or captured soldiers. This was his greatness! He treated individual based on unbiased principles (it may be debated whether that were right or wrong). But, the point is he remained unbiased and favoured justice. This is the reason he is hailed by common people of Maharashtra.

Conclusion: Shivaji was not secular, but certainly respected other religions. He was certain greater than today’s pseudo-secular politician (Err…In fact, there is no comparison here. Its like comparing Sun with candles).