Do you need a visa to enter Israel?
Most western citizens do not require a visa to enter Israel. Security checks are a serious business in Israel, both when you enter and when you depart. They will ask you various questions about yourself (which they will compare to your documentation), about your stay, and even about previous visits you have taken. When you leave, they will ask similar questions, but also where you have been in Israel if you were given anything, and so on.
You should be aware that many Muslim nations would not let you enter if you have an Israeli stamp/visa on your passport. As a result, when you enter Israel through Ben Gurion Airport, Israel no longer stamps your passport. Instead, you will be given a blue permit, which you must retain with you until you leave the country.
You may be asking if you may enter Israel if you have visited Muslim countries. The answer is yes. However, you may be asked additional questions or have your bags checked...