Praise be to Allaah.
We appreciate your question and your efforts in studying and researching very much, especially since you have achieved such great and true results. Although we believe most strongly that it is essential to become Muslim and that Islam is the only religion which Allaah will accept, because He revealed it as the final religion and way, we do understand something of the difficulty involved in leaving that which one is used to. But the wise person knows that he has to follow the truth even if it becomes clear to him after many years and even if he grew up in a different way. Hence Allaah condemned those who refused to follow the truth because they were following the ways of their forefathers. Allaah says (interpretation of the meaning):
"And when it is said to them: "Come to what Allaah has revealed and unto the Messenger (Muhammad for the verdict of that which you have made unlawful)." They say: "Enough for us is that which we found our fathers following," even though their fathers had no knowledge whatsoever and nor guidance" [al-Maa'idah 5:104]
"And when it is said to them: "Follow that which Allaah has sent down", they say: "Nay, we shall follow that which we found our fathers (following)." (Would they do so) even if Shaytaan (Satan) invites them to the torment of the Fire?" [Luqmaan 31:21]
"And similarly, We sent not a warner before you (O Muhammad) to any town (people) but the luxurious ones among them said: "We found our fathers following a certain way and religion, and we will indeed follow their footsteps." (The warner) said: "Even if I bring you better guidance than that which you found your fathers following?" [al-Zukhruf 43:23-24]
The matter will not be too difficult for you - in sha Allaah (if Allaah wills) - for indeed if you believe in Islaam you will be believing in all of the previous Prophets, and you will be believing in the Divine Books. Allaah says (interpretation of the meaning):
"O you who believe! Believe in Allaah, and His Messenger (Muhammad), and the Book (the Qur'aan) which He has sent down to His Messenger, and the Scripture which He sent down to those before (him); and whosoever disbelieves in Allaah, His Angels, His Books, His Messengers, and the Last Day, then indeed he has strayed far away" [al-Nisa' 4:136]
If you become Muslim, you will not be cut off from the sound roots, for every Muslim believes in the Messiah 'Eesa (Jesus) - peace be upon him - as a Prophet and Messenger, and he believes in the true Gospel - before it was distorted - as a Book that was revealed by Allaah. Maybe it will encourage you to know that everyone who used to believe in 'Eesa and then believes in Muhammad (peace and blessings of Allaah be upon him) will have the reward twice. Hence when the Prophet (peace and blessings of Allaah be upon him) sent his letter to Heraclius, the Christian ruler of Byzantium, inviting him to Islam, he said:
"In the Name of Allaah, Most Gracious, Most Merciful. From Muhammad the slave and Messenger of Allaah, to Heraclius the ruler of Byzantium. Peace be upon those who follow true guidance. I invite you with the call of Islam. Become Muslim and you will be safe. Become Muslim and Allaah will give you your reward twice, but if you refuse, then the sin of the husbandmen will be upon you. 'Say (O Muhammad): "O people of the Scripture (Jews and Christians): Come to a word that is just between us and you, that we worship none but Allaah (Alone), and that we associate no partners with Him, and that none of us shall take others as lords besides Allaah. Then, if they turn away, say: "Bear witness that we are Muslims." [Aal 'Imraan 64 - interpretation of the meaning]." (Reported by al-Bukhaari, 2723)
The Prophet of Islam, Muhammad (peace and blessings of Allaah be upon him) said: "There are three who will be given their reward twice: a man from among the People of the Book who believed in his Prophet, then when he comes to know of the Prophet [Muhammad] (peace and blessings of Allaah be upon him), then he believes in him and follows him; he will have two rewards…" (The hadeeth was narrated by Muslim, 219).
On the basis of the above, the answer to your question is: yes, it is very important, indeed essential, for you to take this step which will change your life, bringing you a life of joy and tranquillity through being close to Allaah and believing in His Oneness (Tawheed), having the pleasure of worshipping and remembering Him, and earning reward by obeying Him and saving these rewards for the Day when man will need every single reward:
"On the Day when every person will be confronted with all the good he has done, and all the evil he has done, he will wish that there were a great distance between him and his evil. And Allaah warns you against Himself (His punishment) and Allaah is full of kindness to (His) slaves" [Aal 'Imraan 3:30 - interpretation of the meaning]
With regard to your name, if it has no meanings that involve Shirk (associating others with Allaah) or Kufr (disbelief), then it is permissible for you to keep your name. The name Ismaa'eel (Ishmael) is very suitable; how could it be otherwise when Ismaa'eel was a Prophet of Allaah of whom Allaah says (interpretation of the meaning):
"And mention in the Book (the Qur'aan) Ismaa'eel (Ishmael). Verily, he was true to what he promised, and he was a Messenger, (and) a Prophet. And he used to enjoin on his family and his people As-Salaat (the prayers) and the Zakaat, and his Lord was pleased with him" [Maryam 19:54-55]
We ask Allaah to help us and you to do that which He loves and which pleases Him, and to guide us to the Straight Path, for Allaah guides whom He wills and He knows best those who are guided.
Sheikh Muhammed Salih Al-Munajjid