Yes, and they had the Scriptures. As long as they stayed true to the Word of God they were fine, but it didn't take long for doctrinal heresy to grow. It was already present as Paul warned throughout the Epistles. There is the true Gospel - Paul penned it in I Corinthians 15:1-4 and warned about the other gospel in Galatians chapter 1.
The early elders created the creeds between 212 and 500. They serve 3 purposes.
1. Define what a Christian must believe.
2. Anything contrary is heresy.
3. Any Biblical issue outside of the creeds is to agree to disagree.
These disagreements have created the various gospel preaching denominations of today. Here is an example. Both sides have long texts with plenty of scripture references backing up their position. This is outside of the creeds so we just agree to disagree. The last 2 web sites defend their positions. Try and prove them wrong.
Quinquarticular Controversy
The diametrically opposed Calvinist and Armenian 5 points
Reformed/Calvinism
TULIP
1. Total depravity
2. Unconditional election
3. Limited atonement
4. Irresistible grace
5. Perserverance of the Saints
Armenianism
1. Free will or Human ability
2. Conditional election
3. Universal Redemption or General Atonement
4. The Holy Spirit can be Effectually Resisted
5. Falling from Grace
For a deeper discussion of the differences go to these web sites,
https://www.gotquestions.org/Calvinism-vs-Arminianism.html
Arminianism vs Calvinism Controversial Passages
https://www.xenos.org/essays/calvinism-arminianism-controversial-passages
There are denominations adhering to Calvinism, Arminianism, and parts of each creating a spectrum of different views of these issues.
Calvinism Armenianism debate
https://en.m.wikipedia.org/wiki/History_of_the_Calvinist–Arminian_debate
Biblical Defense of Calvinism
https://www.fivesolas.com/tulipscriptures.htm
Biblical Defense of Arminianism
http://www.evidenceunseen.com/theology/calvinism-versus-arminianism/biblical-defense-of-arminianism/