No, there is no more useful term. The etymology matters. This is so, even if the so named Christians are oblivious to the underlying etymology.
Paul had this to say in Acts 24:14.
“But this I confess unto thee, that after the way which they call heresy, so worship I the God of my fathers, believing all things which are written in the law and in the prophets".
We see above, the leaders of the people at one time viewed the Disciples as being another way, or sect. Judaism was prone to division and strife, this particular example was just heretical.
We can go back further to Acts ch.4 to see how this fracturing from fringe sect, to separate faith begins.
7 And when they had set them in the midst, they asked, By what power, or by what name, have ye done this?
8 Then Peter, filled with the Holy Ghost, said unto them, Ye rulers of the people, and elders of Israel,
9 If we this day be examined of the good deed done to the impotent man, by what means he is made whole;
10 Be it known unto you all, and to all the people of Israel, that by the name of Jesus Christ of Nazareth, whom ye crucified, whom God raised from the dead, even by him doth this man stand here before you whole.
11 This is the stone which was set at nought of you builders, which is become the head of the corner.
12 Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved."
The etymology matters here because Peter invokes "Kristos". The men he is addressing are also Kristos, because some are of the Priesthood, anointed to minister. Peter is claiming association, and representation of a separate kristos, Jesus of Nazareth, who is not of the lineage of Levi.
This fracturing does not occur at once, but over time. As in ch.4, the Apostles testify again in ch.5. This also functions as a second indictment of the Priesthood. Again they claim Kristos, a separate Kristos. The leaders understand the meaning of this use of kristos, and the blood guilt on their heads:
27 And when they had brought them, they set them before the council: and the high priest asked them,
28 Saying, Did not we straitly command you that ye should not teach in this name? and, behold, ye have filled Jerusalem with your doctrine, and intend to bring this man's blood upon us.
29 Then Peter and the other apostles answered and said, We ought to obey God rather than men.
30 The God of our fathers raised up Jesus, whom ye slew and hanged on a tree.
31 Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins.
32 And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him."
On the other hand, we can look at Islam. If we use the old term "Mohammedan", we loose the concept of what Islam is. Gone is submission, or peace with Allah. Instead is a vague notion of a cultural tie to a long gone historical figure.
To say, There is no Allah but Allah, and Muhammad is his Prophet is vastly different. It is Peace, it is Submission. It is Islam.