The actual verses wanted, I believe, are Matthew 28: 18-20 rather than just verse 20. (New International Version)
18Then Jesus came to them and said, “All authority in heaven and on earth has been given to me. 19Therefore go and make disciples of all nations, baptizing them in[a] the name of the Father and of the Son and of the Holy Spirit, 20and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.”
biblegateway.com/passage/?book_id=47&chapter=28&version=31
(btw, you can look at this verse in a variety of translations at this site, if you are interested). The footnote says that the “in” in verse 19 could also be translated as “into.”
I believe that the issue he is bringing up is that this is attributed to the Resurrected Jesus, so that if one does not believe that the Resurrection took place, one then would also by extension believe that any actions or words attributed to Jesus afterwards did not actually happen.