Now I would remind you, brothers, of the gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to you—unless you believed in vain.
A simple but profound description of truly believing Christians: They hear the Word preached, they receive, and they stand in it. Here the Holy Spirit speaks through Paul to teach us the profound mystery of the faith, that Christ who died also rose again and all who believe in Him have eternal life.
But be careful, for the devil is a master at building large and beautiful chapels wherever God builds a church. The devil is the father of lies, of false teaching, and so clever that he can make even the most contrary of heresies and heterodox ideas sound completely Scriptural.
First, the “gospel I preached to you” is no more and no less than the very Word of God concerning the death and resurrection of Christ Jesus. Jesus Himself said it like this: “Repent and believe the Good News (gospel) for the kingdom of Heaven is at hand!” Should any part of this message be removed or replaced, then there is no longer the Gospel.
Second, this message must be preached. Contrary to popular belief, one cannot be a Christian without hearing the Word, and God gives to His church those who are sent to preach His Word. Many enjoy reading or hearing the Scripture and call it a “good book” and even take pleasure in it, but still have enmity against it when it touches a sore spot in their hearts. This is often the case with liberal theology. They love the teachings that put a smile on their faces and make them feel good about themselves, but they despise and intentionally avoid the teachings that make them uncomfortable or call them to abandon their sinful living. This also happens when persons read a text which very clearly says something, but they reject it anyway for whatever reason. Human reason and opinion, when it gets in the way of what the text plainly says, becomes itself a blind-spot and an idol. Finally, preachers who do not preach the Scripture as it is given to them from God are false preachers and they should be marked and avoided.
Third, the devil constructs many beautiful and attractive chapels around the church when it comes to how the message is “received.” The most common — and most dangerous misteaching in the American churches is that receiving is a work of the human will, a choice/decision, or a movement toward God/a commitment. It flows well with American ideology because Americans are very individualistic and tend toward self-reliance, but it is not the Scripture. In the Greek, the word Paul uses in this passage is 
We should not focus on “our” will, “our” choice, “our” commitment, but always focus on God’s will, choice, and commitment to us, that He chose to send His only Son for us, and Christ committed Himself to us by dying on the cross for us. For this is so much more comforting and foundational than something we think we did on some date in the past.
But we must also be careful not to take this to its rational, bitter conclusion and thus leave the Scripture. God may very well have chose us (before the creation of the world), but nowhere does the Scripture say God “chose” to send people to hell. Sinners who insist in unbelief will be condemned to hell because of their own foolish and stubborn hearts, and not because God, who desires all people to be saved, wanted to condemn them. This is also blasphemy. We must remain faithful to the message and not go beyond what is written.
Finally, Paul also warns the believers in Corinth not to fall away from the Word he preached. Falling away from the faith happens when we let sin reign in our bodies such that we stop believing the message. The message is solid and good and right, but it becomes valueless to an individual when he has made sin his priority and his own flesh his idol.
God who reveals Himself by His Word, thank You for giving me Your Gospel and saving me from sin and death. Help me remain firmly standing in Your Word and keep me from falling away on account of sin and disbelief, so that, on the Last Day, I may receive Your promised inheritance and live forever with You. In Jesus’ name, amen.