The continuity and progression of life is due to the natural contradiction God created. Adam and Eve were created different to be able spawn new lives. The differences between Adam and Eve existed not for the sake of reproduction only but for the two to happily enjoy their life as two different species, a man and a woman, as long as they both live under God’s obedience.
We said: "O Adam! Dwell thou and thy wife in the Garden; and eat of the bountiful things therein as (where and when) ye will; but approach not this tree, or ye run into harm and transgression." [Quran: Al-Baqara (2:35)]
Prophet Muhammad (Salla Allah Aleh Wa Salam) teaches us that God created us different:
Allah created Adam from a handful of dust taken from different lands, so the children of Adam have been created according to the composition of the land. Therefore from mankind we have white, red, black and yellow ones; we have good and evil, ease and sorrow, and what comes in between them. [Hadith: Sahih al Bukhari]
Thus, principally the life on earth is based on the natural contradiction, not similarity, God created. The cause of our problems on earth started when we failed to comprehend the fact that we are created different. Allah says:
O mankind! We created you from a single (pair) of a male and a female, and made you into nations and tribes, that ye may know each other (not that ye may despise (each other). Verily the most honored of you in the sight of Allah is (he who is) the most righteous of you. And Allah has full knowledge and is well acquainted (with all things). [Quran: Al-Hujurat (49:13)]
It is natural that we are different. Even physics laws tell us that only when a positive pole and a negative pole come close to each other a magnetic field or electric current will be generated. The simple rule is opposite attracts not repels. Alas, we don’t abide by this rule; we think that different people will harm us not help us.
It is due to Allah first then a Christian friend that I have never been to nightclubs or bars. Ten year ago, some Non-Muslim lab mates asked me, two other Muslims and our Christian friend to go with them to a nightclub. I was never been to a nightclub before so I didn’t mind going to see with my own eye what I usually see on movies. Besides, my other two Muslim friends were going so I said why not. Our Christian friend on the other hand refused to go because he didn’t want to see lots of women’s skins and people drinking. Allah reminded me through a Christian what is haraam (forbidden). He asks me lots of difficult questions that I don’t have answer to. I never felt annoyed or deceived because of his questions. He likes me because I answer honestly what I know. The fact that he wakes up before 6 am in the morning every day to read from the Bible makes me sure of his love to Allah.
It is only those who don’t understand their religion would rather eradicate others than accept them into their religion.