the sikhs are a muslim heretic sect
no wonder they use allah, could you use any other more obvious example? like the baha'i's?
the closest that comes to the use of Allah is Alaha wich is present in the Aramaic copy Pshitta (or Peshitta) of the new testament as one of the words Jesus used to refer to God, e.g., in the sixth Beatitude, "Blessed are the pure in heart for they shall see Alaha."
First... it is not Allah but Alaha. Jesus didn't use the same word, dialect, tone or whatever... if you want to get into it linguisticlly.
Secondly... since using the same Peshitta that you try and use to proof that Jesus used the word Allah (or something that looks like it), then you must also believe everything else in it... including His diety, crucifixion and ressurection
Thirldy Since Allah is a title and not a name. It can be used for any God, like you said the Sikhs use it, the bahai's, mostly arabic religions... figures really.... yet if we translate the title of the roman pagan chief God Zeus (who's title was spoken too as Deus) into Arabic then Zeus was Allah too.
Therefore it doesn't matter what name Jesus use of words were, i bet he even once in his life reffered to God in greek, does that mean that the greek perspection of Deos is the correct one? No it doesn't, in a same way will Islam have nothing to do with Jesus use of words... merely because a heretic religion uses the same dialect.