In the lecture How to Learn Agadah and Midrash, Rabbi Jesse Horn describes the different approaches towards the origins of midrash (e.g., Har Sinai versus Chazal's derashot) and how it should be learned. For example, Shmuel HaNagid - according to most interpretations - takes a rationalistic approach. Midrash is hashkafah and one has the right to disagree with it. However, Rabbi Dessler in Michtav M'Eliahu says that what Shmuel HaNagid really means is how much time one needs to devote to aggadah. If you don't know what it means, just move on to the more essential halachic discussions. [Dessler feels that this represents a defect in one's understanding, rather than implying anything about the content of the midrash itself.]
Horn then discusses Ramban who says - regarding Midrash Aggadah - that one can choose whether or not one wants to believe them. There is no loss if one rejects all of them. Take it or leave it.
At first glance, this seems to be the non-R. Dessler approach towards understanding aggadah. However, Rabbi Yaakov Kamenetsky - in his commentary on Bereshis 44:18 - does not accept that Ramban actually believes this. One needs to realize the context in which it was said. The Ramban was in the middle of a public debate with Christian theologians. "The Ramban - if he would have said that he accepted everything in midrash they would never have accepted it - he would have looked silly. Therefore, the Ramban made a trade off. I'm willing to say something that I don't fully subscribe to in order to win the debate."
"Parenthetically, it's worthwhile to note - how much are we willing to deviate from the truth, to shy away from emes in order to win debates?", asks Rabbi Horn.
It's a rhetorical question, for that is not the subject of the lecture. But once again "lying for the sake of heaven" rears its head. Certainly Ramban - if he indeed did not fully accept his own words - was thoroughly justified in preventing any possible danger to the Jewish community. A similar motivation is perhaps why kiruv organizations like Aish Hatorah play fast and loose with the truth. To them, only Orthodoxy represents the correct belief system and anything less than this is a threat to the future of Jewry. Intentional deception and outright lies are simply means justifying the end. Perhaps they are even relying on the examples of "divine deception" found in the Torah itself! Think Yaakov stealing Esav's blessing, or Moshe's request to Pharaoh for a 3-day holiday. Both are examples of lying to save the future of Jewry.
It isn't about emes. It is about "winning the debate".