It is true that some preach Christ out of envy and rivalry, but others out of goodwill.
Philippians 1:15, NIV:

What was the attitude of those who were preaching Jesus Christ from envy and strife?
They were contentious, preaching the Gospel from a wrong motive. “Those preaching from envy and strife were nonconformist. But apparently, they were jealous of the attention Paul received, and they determined to sow seeds of friction in order to cause him trouble. “Some indeed preach Christ even of envy and strife-What was the ground of this “envy and strife” the apostle does not mention. It would seem, however, that even in Rome there was a party which was jealous of the influence of Paul, and which supposed that this was a good opportunity to diminish his influence, and to strengthen their own cause.

(So, we being Christians need to make sure that we test everything so that we recognize what is false and so that we reject false teachings. This is not saying here that what these people are teaching is false, but rather it indicates that what they are teaching is the true gospel.)