Jesus spoke out against the ways of the fundamentalists of his time. But he never taught that we should directly oppose them. His teaching is that I should concentrate on doing the right thing and not waste time judging others.
(The best I seem to do is that I sometimes keep myself from expressing my judgements. I am still working on the actually not judging.)
So, I have come to accept that fundamentalism is always going to be there. Because the fundamentalists are vocal, they are going to widely been seen as exemplars of the faith even though they are not. That is not for me to correct, as much as I might want to. The task laid for me is not to fight that but to simply worry about my own path.
Doing so, I can sow seeds among those who I have direct contact with. But sowing the seeds is not the purpose but a side-effect. If I am making choices in order to sow seeds, I am not sowing authentic seeds. When I concentrate on my path, then the seeds will sow themselves.