They not only would have the same level of growth, they would have membership numbers far in excess of what they have today. Allow me to explain:
Their constant beating of the Armageddon drum leads them to engage in the following practices:
1) Manipulation and mind control tactics to maintain the sense of urgency among its members. When a group tries to maintain a never-ending perpetual sense of urgency, they must have mechanisms by which they can manipulate the minds and emotions of their members to maintain the urgent atmosphere. The manipulation and mind control tactics are one of the biggest factors that cause members to leave the organization. If the organization did not engage in their Chicken Little-style "end is near" drumbeat, there would be far less need to use psychological manipulation and coercion tactics.
2) A policy of discouraging higher education among its youth. If the organization took a "hands off" approach toward the educational decisions of its members, there would not be as high of a turn-over rate as there is now. People could pursue more invigorating and financially rewarding occupations. With more income, they could contribute more money to the organization.
3) Neglecting charitable activities such as soup kitchens, youth programs, drug and alcohol recovery support groups, and the like. Many burned out and depressed JWs would have remained in the organization had they had the option of engaging in various charitable / community activities such as helping the homeless. Instead, the organization asserts that the only legitimate means of helping the community is by distribution of its literature. This is such a backwards, regressive mindset that causes many JWs to leave.
I believe that these three factors are a direct result of the organization’s irrational and hysterical obsession with the end of the world. If they were an organization that had better educated members, and was known for engaging in charity work in the communities, they would attract and retain more members. After all, the International Red Cross has more members and volunteers than JWs. Why do you think that is?