Isn opposition to immigration racist?
Not unless you define the word racist to make it so. The word has a wide range of meanings, but it is often used just as a term of abuse. Most of those who use the word rarely say what they choose to mean by it. If they did explain it, their own beliefs might be seen to fit. In any case, we must not be prevented from saying what we believe to be necessary for the survival of our country by those who use abuse to try to silence those they disagree with.