There are many things that many people refer to as the good news of Jesus Christ, and not all of them pass Biblical or even intellectual muster. How can we tell the difference between what is real and what is not?
There are a few things that come to mind immediately. The gospel is not for gain. The Gospel is not for our own selfishness. The Gospel is not for emotionalism. The Gospel does not take a series of seminars to explain. I can say it in a paragraph of writing in simple enough terms for a child to understand. (Jesus died in our place to make a way back to God when we did not have one because we gave it up a long time ago, and when we ask forgiveness from God, he makes us holy like He is so we can follow Him.)
There is a litany of other things that fall into that category. There are what some have called “Jesus-plus” gospels, where Christ’s work has to have something added for it to be real. (One of the biggest of these that I’ve seen is that we must also be baptized to be saved, but that stems from a misunderstanding of the difference between justification and sanctification and is the topic for another article.) There are others that claim they are an alternative to Jesus, making Jesus less than God (like calling Him a mere prophet or Teacher) or that He is not necessary at all to the process of our “enlightenment,” or “ascension,” or whatever other spiritual name they give it.
After all that, the absolute best way to defend the truth against these “other Gospels” that Paul references in Galatians 1 is to first KNOW the truth. When an officer for the Canadian Mint or the US Treasury examines a currency note and finds it to be counterfeit, it is because they have studied the real thing so closely that all the fakes announce themselves.
The next step to that is to PRACTICE the truth, or walk with the Lord Jesus, or follow Him, however you want to identify yourself as being His disciple. As you do this, God will begin, through His Holy Spirit, to reveal truth to you. That truth will ALWAYS be verifiable by His word, read in context. There will be no need to attend a 5-part seminar or take a trip to wherever to understand it.
God bless you as you seek, find, and share His truth for everyone.