Final answer:
Scholars question the authorship of Colossians mainly due to variations in writing style and advanced theological concepts, suggesting it may have been written after Paul's time by someone else within the Pauline tradition.
Step-by-step explanation:
Scholars question the authorship of Colossians primarily because the writing style differs from Paul's other letters, and there are theological concepts that seem advanced for Paul's time. Among the reasons given, scholars focus on the second point: the notion that the Christians already participate in Christ's resurrection. This idea indicates a later theological development, which some scholars believe was not present during Paul's lifetime. Instead, it suggests a time when early Christians had further developed their beliefs about resurrection and life in Christ.
Another reason for questioning the authorship is the difference in language and style compared to Paul's undisputed letters. Orthodox acceptance and early Christian writings do not weigh heavily against Pauline authorship in most scholarly discussions about Colossians.
However, the claim that Timothy co-wrote the letter is not a significant reason for doubting Pauline authorship, and acceptance by early Christians does not necessarily confirm or deny the true authorship, as acceptance could be based on its content and alignment with Christian theology rather than direct knowledge of the author.