Ibn Taymiyyah said:
“He (Imaam Ahmad) did not make takfeer of the Murji’ah who say that faith is saying without action, nor did he make takfeer of those who considered ‘Alee more virtuous than ‘Uthmaan, rather the texts are clear from him that he prevented even takfeer of the Kawaarij, the Qadariyyah and others besides them. In fact, he only make takfeer of the Jahmiyyah for their denial of Allaah’s names and attributes, and this is because of their clear and apparent contradiction to what the Messenger (saw) came with, since the reality of their claim amount to denial of the Creator. But he suffered at their hands until he knew their reality very well, seeing that it was founded in ta’teel. Indeed takfeer of the Jahmiyyah is well known from among the Salaf Imaams.
Yet Imaam Ahmad did not make takfeer of the individuals among them, because the one who invites to an idea is worse than the one who simply utters it. And the one who punishes those who oppose such ideas is worse than the one who simply invites to them. And the one who makes takfeer of those who oppose him is worse than the one who punishes them. So in this light, the people in authority were uttering the ideas of the Jahmiyyah, that the Quraan is created, and that Allaah would not be seen in the hereafter, etc., and they were also inviting people to accept these ideas, and inquisiting them over them, punishing them when they did not accept, and making takfeer of those who rejected them. They would keep the prisoners as captives until they uttered the Jahmiyyah belief that the Quraan was created etc., they would not give anyone a position of authority, nor give anyone any provision from the bayt al-maal unless he had these things.
With all these factors present, Imaam Ahmad, may Allaah have mercy upon him, had mercy with them, he sought forgiveness for them, because he knew that it was not clear to them that they were denying the Messenger (saw), nor that they were rejecting what he came with, but they were rather uttering mistaken interpretations, following those who brought such ideas to them.” [Majmoo’ Al-Fataawaa, 23/342]