The whole issue is when people put John Calvin above the Word of God. Some preachers I know do not agree with TULIP while having a slightly different view of Total Depravity and the Perseverance of the Saints saying that true conversion has nothing to with Unconditional Election, Limited Atonement and Irresistible Grace, they do agree with Calvin at certain points but say, "We can agree with some things Calvin says but the Bible stands above Calvin." These are the non-Calvinist brothers and sisters in Christ stating such words that even if they do not fully agree with Calvin but they do agree on some of his sayings. Amen to that.
It is okay to quote some things by Calvin but some practices like infant baptism which some Protestant denominations practice (ex. Presbyterianism) are some things I reject. I could agree with Calvin's statements on authentic faith, on genuine conversion and the Bible but the Bible stands above it. The King James translators were indeed Calvinist scholars, many hymns were written by Calvinists but Calvin is not the final authority.
Even the term Calvinism was only named after Calvin, not Calvin naming his doctrine as Calvinism. Calvin did a good job teaching the doctrine of Matthew, Mark, Luke and John but it did not mean he was free from error. After all, he was just a human being.