If you now voluntarily acquire a foreign nationality, you will no longer be required to give up Belgian nationality. You can find further information under the section Loss of the Belgian nationality.
If you are a Belgian citizen and you automatically receive another nationality (= without having taken any steps to do so, e.g., at birth because your parents have a different nationality), you will not lose your Belgian nationality because of this and can therefore have two or more nationalities.
If you hold another nationality and obtain Belgian nationality, the Belgian authorities will not ask you to renounce your original nationality. It is nevertheless advisable that you consult your national authorities to find out whether the acquisition of Belgian nationality would result in the loss of your original nationality, according to the legislation in force in your country.
You will always be considered a Belgian citizen by the Belgian authorities.