There are many doctrines in the Bible people can agree to disagree. But when someone attacks the gospel of Jesus by saying that one cannot be saved without being water baptized and that baptism washes sins away, etc, that is blatant heresy on the most important doctrine in the Bible! It's not just a matter of disagreement! Paul disputed with the people in Acts chapter 17!(was that wrong?) Paul also hated how the Jews kept adding to the gospel(whether it be circumcision, other works, etc). That is what my contention with certain people on the BDF are. A select few who teach salvation by works which is an attack on the Bible whether people realize it or not! Catholicism is popping it's head up on the BDF more and more as apostasy grows in these latter days!
"Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints." Jude 1:3