If a large amount of doctrinal knowledge is not necessary to be a servant of God, then what are the key attributes?
An important qualification must be humility. While many heard Christ's teachings but proudly continued on their own path, each apostle immediately gave up all he had simply for the opportunity to follow Jesus and learn from Him.
Throughout all of Christ's mission, his apostles did not seek to teach or correct Christ; rather they sought counsel from Him. They asked for more and more, even after reprimands.
Near the end of His earthly mission, after all they had been through together, Christ turned to his friends the apostles and said "One of you shall betray me." Where so many would take offense at such an accusation, or at least brush the comment aside as being not worth their consideration, the apostles still took the humble approach. They each asked "Lord, is it I?"
When I hear or read divine messages, do I pick and choose which to pay attention to? When a fault is suggested, defensiveness should not be my initial reaction. Humility requires sincerely asking the apostolic question.