"He who fights in order that the Word of Allah remains the supreme, is considered as fighting in the cause of Allah". من قاتل لتكون كلمة الله هي العليا فهو في سبيل الله ]

8 - وعن أبي موسى عبد الله بن قيس الأشعري رضي الله عنه قال : سئل رسول الله صلى الله عليه و سلم عن الرجل يقاتل شجاعة ويقاتل حمية ويقاتل رياء أي ذلك في سبيل الله ؟ فقال رسول الله صلى الله عليه و سلم : [ من قاتل لتكون كلمة الله هي العليا فهو في سبيل الله ] متفق عليه.
8- Abu Musa Al-Ash`ari (May Allah be pleased with him) reported that Messenger of Allah (PBUH) was asked about who fights in the battlefield out of valour, or out of zeal, or out of hypocrisy, which of this is considered as fighting in the cause of Allah? He said: "He who fights in order that the Word of Allah remains the supreme, is considered as fighting in the cause of Allah".
[Al-Bukhari and Muslim].

Commentary: Since one's action will be evaluated in terms of intention, so he alone would be a Mujahid (warrior in the cause of Deen) who fights to glorify the Name of Allah.