It doesn't matter what your opinion is on this issue. The law in effect at the time of Obama's birth determines it. According to that law, if Obama was born abroad to an alien father and an American citizen mother less than 19 years of age, he was not an American citizen at birth. There, that settles it!
If an illegal alien can cross the border and drop a baby one foot inside our country and it be considered a citizen, I am not optimistic that your argument will win the day.