I think that's harsh. I'd say that---assuming that they are Christians---that they are simply ignorant.All cults and false religions have one thing in common. They all dishonor God and insult his Son Jesus Christ. It is because of this that we know they are Satanic. It is the work of the Holy Spirit to honor God and glorify his Son Jesus Christ.
Why are you the judge, jury and executioner here? What are your credentials? What is your office in the Church?Calvinism teaches that God predestinates people to hell before they are ever born. What a terrible thing to believe about God. There is no way that a person that teaches such a thing is indwelt with the Holy Spirit. What they are indwelt with is the Spirit of Satan. It is not humanly possible to have saving faith in the God of Calvinism or any other religion that dishonors God with that kind of teaching.
Some people might misunderstand you to be teaching universalism with this particular critique.Calvinism is a direct attack on the Lordship of Jesus Christ. Jesus claims to be the savior of the whole world, Jesus said, "I came not to judge the world, but to save the world" John 12:47. Calvinist teach that Jesus did not atone for the sins of the world, scripture says just the opposite. "That he by the grace of God should taste death for everyone" Hebrews 2:9. If Jesus did not defeat sin, death and the devil, then Jesus is not Lord. If Jesus is not Lord, then no one is saved and we are all still in our sins without hope. Calvinist teach that Jesus only atoned for some sins, but not all sins. This kind of teaching is an insult to God the Father and his Son Jesus Christ. If there had been one sin that Jesus did not atone for God would not have accepted Jesus back into heaven, nor would God have made Jesus both Lord and Christ, Acts 2:36.
Calvinism isn't a religion, it's a school of theology or of theological thought.How to escape this dreadful religion called Calvinism. Renounce these dreadful beliefs that dishonor God and insult his Son Jesus Christ and call upon Christ to save you. "Whosoever that shall call upon the name of the Lord shall be saved" Romans 10:13. Calling on Christ to save you is an act of faith. Jesus saves and he saves to the uttermost, Hebrews 7:25.