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 Qur'an:

Alms shall be used only for the advancement of God's cause, for the ransom of captives and debtors, and for distribution among the poor, the destitute, wayfarers, those that are employed in collecting alms, and those that are converted to the faith. That is a duty enjoined by God. He is Wise and All-knowing. (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 Qur'an 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 nowadays. According to this interpretation, the above injunction is really no longer applicable.

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The words "for the cause of God" are general in their application. They include any task that is performed for God's cause, being especially applicable to that work which the Qur'an calls "calling to the service of God." The true objective of Islam is preaching, not fighting. Calling people to submit themselves to God is the Islamic point of departure; war is only resorted to when the other party starts hostilities, and forces the preachers of Islam to take up arms to defend themselves.

The Egyptian scholar, Rashid Raza, has noted in his commentary of the Qur'an that the words "for the cause of God" are equally applicable to those who strive to spread the word of God.

The best way to give alms "for the cause of God" in the present age, is to contribute to the training of preachers, and to their dispatch by Islamic organizations to non-Muslim lands, and to continue to give financial support to these preachers, just as non-Muslims do for the propagation of their religion. (Tafseer Manar)