Here is the article on the Stand to Reason web site, written by Greg Koukl.
The six essential doctrines would be: the Trinity, the deity and humanity of Christ, the bodily resurrection, man’s fallenness and guilt, salvation by grace through faith by the substitutionary atonement of Jesus Christ, and belief that Jesus is the Messiah. And you have a seventh doctrine that strikes me as a functional necessity, that is the ultimate authority of Scripture without which none of the other truths can be affirmed or asserted with confidence.
By the way, it’s really important that people know these doctrines because many Christians are quite kind-hearted and they end up not being very careful about drawing distinctions between truth and falsity because they don’t want to disagree. I understand that. But if you were really kind-hearted then you would be honest and straight-forward with people about the demands of the gospel on their lives. The demand of the gospel is that you believe particular things to be true. It’s not just a matter of mere belief, as if these are just some incidental details of theology that you might happen to be mistaken about. And if you just happen to be mistaken, why should you go to hell because of that?
You don’t go to hell because you just happen to mistake a doctrine. You go to hell because you have broken God’s law. It is very critical to understand that. God only judges guilty people. People get judged by God not because they mess up on their theology but because they are guilty. People who are guilty get condemned. That’s it. There is a way to get around that but you’ve to know a couple of particular things that are true before you can take advantage of the forgiveness God offers. That’s where the essential doctrines come in.
He’s writing from a Calvinist perspective, which I don’t entirely agree with. But I don’t see anything wrong in that minimal list. Sometimes, it’s a good thing for us to focus on the essentials. There are lots of Christian denominations, and they disagree on many minor things, but on the major things, they are in agreement. And that’s a good thing, too.