Benefits of Circumcision in Islam
Question

Being not a religious person I wonder why (Jewish and) Islamic people consider circumcision obligatory. It seems to me that a Muslim considers every human being as a perfect creation of Allah. So why doubt this perfection by changing God’s creation? I know of course about hygienic considerations, but I really hope that you can give an answer to my question. Thank you for your kindness.
Praise be to Allah.The Significance of Following Islamic Commands
The Muslim obeys the command of Allah. This is the meaning of Islam, which is submission to Allah and obedience to His command, whether the wisdom behind it is clear to him or not, because the One Who is issuing the command – Allah, may He be Exalted – is the Creator, the All-Knowing, the All-Aware, who created mankind and knows what is good for them and what is not good for them.
Importance of Circumcision in Islam
Circumcision is one of the rulings of Shari`ah which the Muslim carries out willingly, in submission to and out of love for Allah, and seeking reward with Him. He is certain that Allah does not command anything unless there is wisdom behind it and it is good for His slaves, whether people know that or not. Since your question referred to the health benefits of circumcision, we will, after looking at the Shar`i (religious) benefits, will answer your question about the health benefits, in order to increase the believers in faith in the ruling, and so that non-Muslims may see one aspect of the greatness of this Shari`ah (Islamic law) which came to bring benefits and ward off harm.
Religious Benefits of Circumcision
Circumcision is one of the commands concerning beautification enjoined by Allah, which Allah has prescribed for His slaves to make them beautiful both outwardly and inwardly (physically and spiritually).
It is the perfection of the Fitrah (natural disposition of humans) with which He created them, and hence it is the perfection of the Hanifiyyah (pure monotheism) of the religion of Ibrahim (Abraham).
The origin of the institution of circumcision as the perfection of Hanifiyyah was when Allah made a covenant with Ibrahim (peace be upon him) and promised to make him an Imam (leader) of mankind, and promised him that he would be the father of many people, that prophets and kings would come from his loins and that his descendants would be many.
And He told him that between him and his descendants there would be the sign of the covenant, which would be that every newborn male among them would be circumcised, and so the covenant would have this sign on their bodies.
Circumcision is a sign of having entered into the religion of Ibrahim, and this is in accordance with the interpretation of the verse (interpretation of the meaning) –
{[Our Sibghah (religion) is] the Sibghah (religion) of Allah (Islam) and which Sibghah (religion) can be better than Allah’s? And we are His worshippers.} [Al-Baqarah 2:138] – as referring to circumcision.
For the Hanifs (pure monotheists, i.e., Muslims), circumcision has the same status as baptism does for the worshippers of the cross (i.e., Christians). They purify their children – as they say – when they baptise them in the baptismal water, and they say, now he has become a Christian. Allah has prescribed for the Hanifs their own rite, the symbol of which is circumcision. Allah says (interpretation of the meaning):
{[Our Sibghah (religion) is] the Sibghah (religion) of Allah (Islam) and which Sibghah (religion) can be better than Allah’s? And we are His worshippers.} [Al-Baqarah 2:138] –
… So Allah has made circumcision a symbol of those who belong to Him and to His religion, and who attribute themselves to Him as being utterly enslaved to Him alone…
The point here is that the religion of Allah is Hanifiyyah (pure monotheism) which fills the heart with knowledge and love of Him and sincerity towards Him, and worship of Him alone with no partner or associate, and which marks the body with the characteristics of the fitrah, namely circumcision, removal of the pubic hair, trimming the moustache, cutting the nails, plucking the hair from the armpits, rinsing the mouth, rinsing the nose, using the Siwak (toothbrush made from twigs from a certain tree) and cleaning oneself after elimination of urine or faeces.
So the Fitrah of Allah is manifested in the hearts of the Hanifs and on their bodies. (End quote from Tuhfat Al-Mawdud bi Ahkam Al-Mawlud by Ibn Al-Qayyim, p. 351)
Circumcision also has health benefits and brings a lot of benefits to the boy in his life. (Please see Question # 2425).
It is not essential for the child to remain as he is when he comes forth from his mother’s womb, if there is something that may be done for him that serves a purpose and is enjoined by the pure religion. Such things include shaving his head after he is born, because that is in his best interests. The Prophet of Islam (peace and blessings of Allah be upon him) said: “Remove the harm from him.”
The same applies to washing the blood from him and cutting the cord by which he was attached to his mother, and other things which are done to benefit him.
Health Benefits of Circumcision
Dr. Muhammad `Ali Al-Bar (a member of the Royal College of Surgeons in the UK and a consultant to the Islamic Medicine department of the King Fahd Centre for Medical Research in the King Abd Al-`Aziz University in Jeddah) says in his book Al-Khitan (Circumcision):
“Circumcision of newborn boys (i.e., within the first month of life) brings numerous health benefits, including:

Protection against local infection in the penis, which may result from the presence of the foreskin, causing tightening of the foreskin, which may lead to retention of urine or infections of the glans (tip) of the penis – which require circumcision in order to treat these problems. In chronic cases, the child may be exposed to numerous diseases in the future, the most serious of which is cancer of the penis.
Infections of the urethra. Many studies have proven that uncircumcised boys are more exposed to infection of the urethra. In some studies the rate was 39 times more among uncircumcised boys. In other studies the rate was ten times more. Other studies showed that 95% of children who suffered from infections of the urethra were uncircumcised, whereas the rate among circumcised children did not exceed 5%.

In children, infection of the urethra is serious in some cases. In the study by Wisewell on 88 children who suffered infections of the urethra, in 36 % of them, the same bacteria was found in the blood also. Three of them contracted meningitis, and two suffered renal failure. Two others died as a result of the spread of the micro-organisms throughout the body.

Protection against cancer of the penis: the studies agree that cancer of the penis is almost non-existent among circumcised men, whereas the rate among uncircumcised men is not insignificant. In the US the rate of penile cancer among circumcised men is zero, whilst among uncircumcised men it is 2.2 in every 100,000 of the uncircumcised population. As most of the inhabitants of the US are circumcised, the cases of this cancer are between 750 and 1000 per year. If the population were not circumcised, the number of cases would reach 3000. In countries where boys are not circumcised, such as China, Uganda and Puerto Rico, penile cancer represents between 12-22 % of all cancers found in men; this is a very high percentage.
Sexually transmitted diseases (STDs).Researchers found that the STDs which are transmitted via sexual contact (usually because of fornication/adultery and homosexuality) spread more among those who are not circumcised, especially herpes, soft chancres, syphilis, candida, gonorrhoea and genital warts.

There are numerous modern studies which confirm that circumcision reduces the possibility of contracting AIDS when compared to their uncircumcised counterparts. But that does not rule out the possibility of a circumcised man contracting AIDS as the result of sexual contact with a person who has AIDS. Circumcision is not a protection against it, and there is no real way of protecting oneself against the many sexually transmitted diseases apart from avoiding fornication/adultery, promiscuity, homosexuality and other repugnant practices. (From this we can see the wisdom of Islamic Shari`ah in forbidding fornication/adultery and homosexuality).

Protection of wives against cervical cancer. Researchers have noted that the wives of circumcised men have less risk of getting cervical cancer than the wives of uncircumcised men. (End quote from Al-Khitan, by Dr. Muhammad Al-Bar, p. 76)

And Allah knows best.
Reference: Professor Wisewell, published in the American Family Doctor Magazine, issue no. 41, 1991 CE.