A quick google search revealed that both the quotations have been copy pasted from the website of Lahori Jamaa't. http://ahmadiyya.org/movement/maudoodi/letter.htm
Regarding the Lahori Muhammad Ali, I doubt Deedat would need to rely on his works since refutations of Christianity have been around for centuries- many Muslims studied and refuted the Bible including the likes of Ibn Taymiyyah. Not to mention Christian works regarding things like textual criticism, higher criticism etc have been around for centuries also so refutations of Christianity is nothing new