Yes it is. Hence the use of the word "killing" in the definition that you yourself provide: I also defined killing, please try to keep up.
Note also the use, in your own definition, of the word "systematic". There is nothing "random" about Muslim immigration.
For one person to marry a person of another race kills no-one, nor is it "systematic". It would be one or more less babies born of the single heritage, ending that heritage one bit at a time, over generations.
And you know this how? Do none of your family come from the Danelaw? Any Celtic blood? I have posted on this already. Feel free to look it up.
So, let me ask you again, what are the defining features of your "culture"? I assume this is a rhetorical question? Regardless, it will not get answered here, to be ridiculed by you.
If you do not wish to be called a racist, you have the option of not expressing racist views. I have already given a definition of racism, in the event you do not own a dictionary. I believe all men are created equal. I also have more in common with people the same skin tone as me. I find it hard to identify with Native Americans, for instance, as I have no frame of reference or common ideology.
None of which involved enforcing an opinion such as Holocaust Denial. Thought, last I checked, is still free.