Zakat, or the alms-tax, is one of the five basic tenets of Islam. Its payment is obligatory, at the rate of 2.5%, on all wealth that is subject to growth. Eight categories of people, eligible to receive Zakat, have been specified in this verse of the Quran:

Alms are only for: the poor and the destitute, for those who collect Zakat, for conciliating people's hearts, for freeing slaves, for those in debt, for spending for God's cause and for travellers in need. It is a legal obligation enjoined by God. God is All-knowing and Wise.THE QURAN 9: 60

So, as is clear from this verse, one of the ways that Zakat can be spent is 'for the cause of God'. Though the words of the Quran are general, the consensus of Muslim theologians is that they refer to holy war: it is those who are voluntarily engaged in holy war, and have not been appointed any salary by the government, who should receive alms given 'for the cause of God'. (Fiqh-us-Sunnah, Vol. I, p. 393)

If we accept this interpretation, then it means that the instruction to give Zakat 'for the cause of God' may, to all intents and purposes, be misapplied. This form of voluntary participation in wars was only possible in ancient times; under modern conditions there is no question of it. In the present age, war has become so complicated and technical that only those who have received regular training are able to take any real part in it: to allow untrained people to enter the field of battle is tantamount to inviting defeat. In other words, only those who are employed by the government can participate in war. According to this interpretation, the above injunction is really no longer applicable.