Where to begin?
When ever I have debated homosexuals I just plain ask them is being gay natural, or unnatural?
1) Whenever is one word, not two. -1
2) Comma after homosexuals and after them. -2
3) Since you start out in the past tense, you need to continue in the past tense. Or, if you wish to make your argument in the present tense, you need to start in the present tense. The sentence should read "Whenever I have debated homosexuals (in the past), I would just plain ask..." or "Whenever I debate homosexuals (in the present), I just plain ask..." -1
4) Since you are quoting (you are quoting a comment you use), the phrase "is being gay natural, or unnatural?" should be enclosed in quotes, as above. -1
....They always say its natural then I say why cant two homosexuals have children together?
1) An ellipse has only three dots. Also, it is unnecessary to use it here. -2
2) Period after "natural." You are ending a thought and starting a new one. -1
3) Apostrophe between the "n" and the "t" in can't. -1
4) Why does the purpose of any relationship have to be children? -.5 since this is not a grammatical comment.
5) Because you are making a contraction of "it is," you need an apostrophe in "it's." -1
Then I tell them because its not natural, then I tell them look at a man and a woman they can have children together because its natural...
1) Again, you are quoting yourself, so "because its not natural" needs to be in quotation marks. -1
2) Again, you are making a contraction of "it is," you need an apostrophe in "it's." -1
3) Period after natural, not comma. Again, you are completing one thought and starting a whole new one. -1
4) You really don't need the second "then" here. The sentence(s) should read, "Then I tell them, "because it's not natural." I tell them...etc -1
5) The second sentence should read, "I tell them to look, or, "I tell them, "look at...etc." -2
6) Comma after woman. -1
7) Proper form of the ellipse (ie, three dots, not four). However, given your previous mis-use, I suspect this was an accident. Inproper useage. -1
They usually don't want to argue anymore after I bring up those examples.
1) It's not an example, it's an arguement. -1
2) That might be because the arguments are fairly stupid. Again, why is reproduction the only purpose for a relationship? -.5 since this is not a grammatical comment.
Overall, you have rated a -20 on my grammar scale. A zero would be an average post (ie, either no errors, or one or two minor ones that are the result of just missing them while proofreading).