1CO 15:1 Now, brothers, I want to remind you of the gospel I preached to you, which you received and on which you have taken your stand. 2 By this gospel you are saved, if you hold firmly to the word I preached to you. Otherwise, you have believed in vain.
1CO 15:3 For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures, 4 that he was buried, that he was raised on the third day according to the Scriptures, 5 and that he appeared to Peter, and then to the Twelve. 6 After that, he appeared to more than five hundred of the brothers at the same time, most of whom are still living, though some have fallen asleep. 7 Then he appeared to James, then to all the apostles, 8 and last of all he appeared to me also, as to one abnormally born.
RO 1:16 I am not ashamed of the gospel, because it is the power of God for the salvation of everyone who believes: first for the Jew, then for the Gentile. 17 For in the gospel a righteousness from God is revealed, a righteousness that is by faith from first to last, just as it is written: "The righteous will live by faith."
We are saved by believing the gospel--NOT by doing rituals.
I believe we need to stop arguing with those that are deceived--present the gospel which "is the power of God for the salvation of everyone who believes." I don't believe that we can argue people into believing the truth--only tell the true gospel and leave the rest to the power of God.