Educational scientist and expert on crying and sleep problems in babies
Do not force it if it does not want to. Find other ways to enjoy the water.
You can not fight a child's fear by frightening it further. So let the bathing be for a while and wash it with a washcloth instead.
One never knows what fears prevent the child from dreading the bath he loved before. That is not easy to accept. It seems unfounded to you, but does fear always need a specific reason? You do not need to share the feeling, but you are not the one (or the one) who has to live with it. Before you make fun of it, think about your own fears and ask yourself how "rational" they are. Think about how you would feel if you were not allowed to avoid your fears. Do you like big, harmless spiders, for example?
It helps to tell your child that (honestly) there is nothing to fear, but it is not helpful to tell him not to be afraid. If you say, "It's absolutely safe, but I see you're scared, so let's use sinks or the big bucket or the tub," then the child feels like you're on his side. If you say, "There's nothing you need to be afraid of, you silly," then you're not providing your child with any security or support.
For most toddlers, fear disappears as fast as it has come, especially when tactfully handled. You can speed it up with lots of water fun that has nothing to do with bathing or the bathroom. If your child can not stand a paddling pool, try a wash bowl and cups to refill and empty.
Maybe it's fun to visit a swimming pool, where it's allowed to stay in your arms all the time, and experience how fun water is with a mug or a watering can. But if it's just scary, you'd rather leave the pool without blaming your child. The more calm and understanding you react, the faster your fear can disappear again.