Complex sentence: Williams regarded the study of Sanskrit as a means to an end, namely the conversion of India to Christianity, whereas for Müller, the work (while it would assist missionaries) was also valuable as an end in itself.
Split into simpler sentences: Williams regarded the study of Sanskrit as a means to an end, namely the conversion of India to Christianity. For Müller, the work, while it would assist missionaries, was also valuable as an end in itself.