Firstly — The non-Ahmadi Muslim stops short of accepting the full implications of the Quranic verse which declares the Holy Prophet Muhammad to be Khatam an-Nabiyyin — i.e., the Last Prophet. The obvious corollary of this position is that the Holy Prophet Muhammad has been vested with mankind's spiritual leadership for all time. The non-Ahmadi Muslim's belief that about the end of the world, Jesus Christ will be sent down from heavens for the reformation of the world amounts to the transference of the world's spiritual leadership from the Holy Prophet Muhammad to Jesus Christ, thereby terminating, to all intents and purposes, the Holy Prophet's spiritual dispensation.
The Ahmadi Muslim on the other hand, believes that the Holy Prophet's spiritual leadership extends for all time to come, and the question of Jesus Christ's second coming, therefore, does not arise.
Secondly — Another belief of the non-Ahmadi Muslim which amounts to a denial of Khatam an-Nabiyyin isthat, according to him, the spiritual experience known as "revelation" has come to an end. Now this strikes at the very root of the whole purpose of the institution of prophethood. Prophets were raised from time to time for the express purpose to bring man closer to God — so close as to have a personal experience of His existence and presence. The only means which forges such a personal link between man and his Creator is the spiritual experience known as revelation, in which man becomes the recipient of the word of God. But for such an experience man's faith in the very existence of God lacks that clear-cut conviction which comes when we actually hear someone speaking to us. No doubt the whole universe, with all its wonders of designing and workmanship points to the existence of a Master Mind behind it, and mere rational thinking also inclines us to the conclusion that all this wonderful universe could not have come into being just by accident, that behind it all, there must be a Mind, a Will, a Purpose who has created it, is guiding and controlling it, and ensuring its smooth running. This is indeed what philosophy and science attempt to tell us. But the only conclusion that is reached by this process is that God must be there to run this whole show. But the philosopher's must be ispoles removed from the prophet's is. The prophet tells us from his personal experience that he has heard the voice of God speak to him, and that is the end of all groping and doubting. What was hitherto accepted as only highly probable now becomes a reality as clear-cut as day-light. All clouds of doubt are dispelled. A prophet's appearance, with a clear-cut clarion proclamation that he has seen and heard God, at one stroke illumines the whole landscape of human life, lifting the veil from the mystery of life, and driving home to the deepest depths of the human mind the conviction that God is the only Reality, the very Substratum who sustains all existence and makes life, with all its ups and downs, its sunshines and shadows, meaningful, worth living, even enjoyable. This is the vital role which the institution of prophethood plays in the game of life, and that is why from time immemorial prophets were raised to shed light on life on this otherwise dark and dismal planet.
The advent of the Holy Prophet Muhammad has been likened in the Quran to "rising of the sun" (Sirajan Munira), implying that his spiritual light was meant for the whole of mankind. And Khatam an-Nabiyyin implied that this spiritual sun will keep shining on humanity for all time to come. Denial of the possibility of God speaking to man amounts to switching off the Prophet's spiritual sunshine, thereby undoing the very purpose which his position as Khatam an-Nabiyyin was meant to serve for all time to come. If a Muslim can no longer attain to that spiritual closeness to God which comes only through God's spoken word in the form of revelation, it amounts to the virtual termination of the Holy Prophet's spiritual dispensation.
Against this, the Ahmadi Muslim believes that God speaks to man today as he did of yore, but only to those who are truly steeped in the light of the Quran and the Prophet's Sunnah. The Founder of the Ahmadiyya Movement was a living embodiment of this ever-flowing spiritual blessing of the Holy Prophet Muhammad. The word of God that came to him in profuse abundance reinforced faith in God in this age of wide-spread scepticism, thereby meeting the most dangerous threat to human civilisation which the decay of Faith in the long run spells. All this spiritual illumination came to him, he declared, by drinking deep at the fount of the Quran and the Sunnah. Indeed this abundant gift of direct communion with the Supreme Source of life was vouchsafed to him in implementation of the Quranic declaration about the Holy Prophet Muhammad being Khatam an-Nabiyyin The spiritual tree of Islam is an ever-green tree, bearing fruit in all times, he declared. The non-Ahmadi Islam which shuts out this greatest boon of God's direct personal experience by man is like the fig tree in the Gospel’s parable which had ceased to bear fruit.
Thirdly — Another big difference between an Ahmadi and a non-Ahmadi is that the Ahmadi believes in striving and struggling for the dissemination of the Light of Islam; which is described in the Quran as Jihadan Kabira, the highest/greatest Jihad, carrying the message of Islam to the four corners of the world, at great personal sacrifice in terms of money and worldly prospects. The non-Ahmadi, unfortunately, is still very apathetic to this great duty enjoined by the Quran, which divides Muslims into two categories the Mujahidin and Qaideen, i.e., those struggling and suffering for the establishment of Truth and those who sit back doing nothing. The first group is said to have a higher status with God:
"Those who do Jihad with their wealth and lives carry with God a status higher than those sitting back." (The Holy Quran: 4:95)
The Ahmadi Muslim is a Mujahid, the non-Ahmadi a Qa'id. Both are Muslims, but with a big difference. Islam is a call to striving and struggling for the establishment of God's sovereignty in human heart. Mere acceptance and profession is not enough. The Quran has a poor word for those who say they believe that Islam is the only Light that can save mankind, but, raise not a little finger to make that Light known to the world. They are described as "idlers."