Is it acceptable for all Christians to believe what they want to believe? Of course not. Paul addressed many incorrect beliefs and practices in his letters. Syncretism (mixing of differing beliefs and practices) was alive in biblical days as it is today. This is a place where creeds can be helpful.
What is a creed?
A creed is a commonly-held belief system. In Christianity, there have been many creeds over the centuries: Apostle’s Creed, Nicene Creed, Athanasian Creed, and more. Many churches and denominations required people to agree with these creeds in order to identify with the church or denomination. For more examples and information, check out Historic Christian Confessions & Creeds.
Southern Baptists consider the Baptist Faith & Message as a “statement of generally held convictions” but not a creed. Southern Baptists point to scripture rather than a creed, but the value of a creed or a “statement of generally held convictions” is in creating a common core of conversation and understanding.
Common Language Needed
People in a discipling relationship often enter with very divergent backgrounds and beliefs. Any “commonly held convictions” are useless unless supported in God’s Word. Thus, having a commonly held belief system from which to turn to scripture creates great conversation and understanding.
Am I recommending adoption of a creed? No, but I am strongly encouraging pursuit of common language and understanding for faith and practice. Be careful ignoring doctrine in your disciple-making efforts. Doing so can result in a lack of biblical skills for building correct faith and practice.