The Salaf used to seek knowledge for the sake of Allāh, and they were ennobled and then became Imāms of Guidance, by whom the people guided themselves.
If we were to say that there is no rejection to be shown in issues of difference in an unrestricted manner, then the religion as a whole would disappear...
If the person intends the issues of differing (khilāf) [that no rejection is shown towards them], then this is false, it opposes the consensus of the ummah.
The issues of khilāf are broader than the issues of ijtihād and it is permissible to differ in the issues of ijtihād where there is more than one view being supported by evidence.
However, due to the preponderance of ignorance, and scant knowledge of the remnants of the messengership amongst many of the latecomers, takfīr is not made of them...
If I see someone invoking the (dead) in the grave, seeking rescue from him, then he has been afflicted with shirk, shall I call him (to the truth) on the basis that he is a Muslim...