Wait a min, I wouldn't let you spin it.
A bit from WIKIPEDIA (even though I do not rely on it for my learnings but it has something with reference here)
The word "shahid" originates from the Qur'anic Arabic word meaning "witness", which is used in the context of "those who bear witness." Its application to Muslim martyrs originates from the context of the martyr having died in the way of Islam and, therefore, having become a "witness" to the "Shahada", i.e. "I bear witness that there is no God but Allah and that Muhammad is the Messenger of Allah."
The word 'shahid' in the Qur'an is used to denote "witness", not martyr. An example is verse 16:89 of the Qur'an:
وَيَوْمَ نَبْعَثُ فِي كُلِّ أُمَّةٍ شَهِيدًا عَلَيْهِم مِّنْ أَنفُسِهِمْ ۖ وَجِئْنَا بِكَ شَهِيدًا عَلَىٰ هَٰؤُلَاءِ ۚ وَنَزَّلْنَا عَلَيْكَ الْكِتَابَ تِبْيَانًا لِّكُلِّ شَيْءٍ وَهُدًى وَرَحْمَةً وَبُشْرَىٰ لِلْمُسْلِمِينَ
Translation: "And on the day when We will raise up in every nation a witness against them from among themselves, and We will bring you (Muhammad) as a witness against these (your people or the other witnesses); for We have revealed (sent down) to you a Book (Scripture) expounding all things clearly, and a guidance, and a mercy, and glad tidings for those who have Surrendered unto Allah (Muslims)." (Al-Qur'an 16:89)
In the Qur'an (verse 3:98), God calls Himself a 'Shahid':
قُلْ يَا أَهْلَ الْكِتَابِ لِمَ تَكْفُرُونَ بِآيَاتِ اللَّهِ وَاللَّهُ شَهِيدٌ عَلَىٰ مَا تَعْمَلُونَ
Translation: "Say: "O People of the Book, why do you reject the word of God when God is a witness to all that you do?" " (Al-Qur'an 3:98)[1]
The etymology of the word "shahid" suggests that it primarily means "witness" and the same word began to be used by Muslims as an honorific title for Muslim martyrs who died fighting in the way of Islam. Subsequently, and over a period of time, the same word was adopted by non-Muslims in the Middle East and South Asia such as Arab Christians and South Asian Hindus and Sikhs to denote their martyrs.
When in Kalma you say I BEAR WITNESS THAT THERE IS NO GOD WORTHY OF WORSHIP EXCEPT ALLAH AND I BEAR WITNESS THAT MUHAMMAD IS HIS SERVANT AND MESSENGER
then the died one "WITNESSED" by ACT as well as WORDS. That is why Shaheed has to be only in the path of ISLAM and Allah to be the one who "WITNESSED" by act.
Now coming back to my point, Shahadat or Shaheed is a Muslim Title. When they use it, they try to become something which is FOREIGN their faith and many ways anti-to-their-faith. Its paradoxical to imagine somebody non-Muslims acknowledging himself as Shaheed.. its wrong and expression of misery that OKAY I DIDN'T HAD anything in my faith but allow me to BECOME SHAHEED even though I am Christian or Hindu or Sikh. Shaheed is not patient and you don't get sued for using it but understand the miserable condition in which this is being "adopted". Give non-Muslim Martyred ones a good name, respect them and present them as heros but they are NOT SHAHEED. P E R I O D.
To explain this aspect further, this would be similar to a situation in which a Muslim named Khalid fought against Hindus (for example) and died fighting but was given name Khalid Ram Bhagt after his death to glorify his death. SOO WRONG!
Lets look through your own point for a moment here, if Shaheed is given to "Muslims and Sikhs" then Muslims have this name by birth but its interesting that Sikhs can become Shaheed after they die but never in their life time? Illogical to the limits possible!