I have encountered plenty of attitudes growing up that anticipate and/or lead to this kind of erroneous view of the Old Testament: “The Old Testament is just history.” “We’re under the New Covenant not the Old.” “The Old Testament just has good information, nothing necessary.” “We’re under grace, not law.” Etc. etc.
Those who use these kinds of quips without thinking – or worse, use them because their beliefs align with them – display a working ignorance of the New Testament authors’ reliance upon the Old Testament Scriptures: 2 Timothy 3:16-17, Luke 24:27, Romans 16:25-27, Galatians 3:8, 2 Peter 1:19-21, etc. — and these are just some passages that specifically use the term “Scripture” when referring to the Old Testament! (See also Ephesians 2:19-21 for the idea of the Old Testament coinciding with the New as a norm in the mind of Paul…)
I try to share useful and/or helpful resources on this blog from time to time – so for more on this subject here are two podcasts where a Biblical Scholar and a pastor give reasons for why they think Andy Stanley’s statements in particular are downright dangerous and unbiblical.
Dr. James R. White on the Dividing Line [time mark 25:04]: http://www.aomin.org/aoblog/2018/05/10/james-cone-eulogized-by-evangelicals-andy-stanley-unhooks-the-old-testament-open-phones-on-a-ton-of-interesting-topics/
Chris Rosebrough on Fighting for the Faith [time mark 39:06]: http://www.piratechristian.com/fightingforthefaith/2018/5/oe7tde2xfb7n4vtw4txdcbklk3xsk2
Updated 6/3/2018: Jeff Durbin responding to Andy Stanley’s remarks: https://www.sermonaudio.com/sermoninfo.asp?SID=531181254507
Here is an article by Dr. Michael Brown that provides even more evidence for the interconnectedness of the Testaments: https://www.christianpost.com/voice/no-pastor-andy-stanley-we-should-not-unhitch-ourselves-from-the-old-testament.html
And here is an article with some good points from a few other thinkers: https://www.christianpost.com/news/theologians-warn-andy-stanleys-message-to-unhitch-old-testament-is-heresy-224026/