Being different is difficult, and that is a blessing.
Leading a change for others is hard for a reason. You are asking someone to leave the safety of “how things are done” to follow you and your ideas. They are taking a risk.
So, of course, they are going to push back. It is the person’s job to do that.
It is our job, as leaders, to understand the risk they are taking to the best of our ability and help them feel comfortable taking it.
When people ask “why?” look at that as a blessing. It is an opportunity to see what is important to them and make your concept that much stronger.
Tension is excellent, and maybe an indicator that you are on the right track.