The answer to this is straight NO, although I think that it will be more effective to fully implement Dhamma if you are Buddhist. Meaning by being a Buddhist is observing Five Precepts (Pancasila), taking homage or refuge to the Buddha, Dhamma and Sangha, engaging in the Buddhist community and chanting Paritta.
In order to practice Dhamma, it is beneficial for us to know what is Dhamma and the nature of it. As quoted from Dhamma Vandana (Homage to the Dhamma verse)
Apparent here and now,
Paccattaṃ veditabbo viññūhi
To be experienced individually by the wise.
For example, the first of Four Noble truth – the basic of all Buddhist teaching,regardless of tradition- is the existence is a Dukkha. Dukkha means that every living being experiences suffering or unsatisfactory-ness in any stage of life. Take an example of buying a new gadget. You have worked like a horse and saved a lot of money to own this gadget. As soon as you buy it, you feel the satisfaction and pride and excitement from things that you can do with this gadget. The following day, you use the gadget and find out the highly advertised features is not working as you have expected. You may feel discontented, unhappy, dissatisfied. That feeling may evolve and become rage and angry and thinking that You should have bought more inexpensive gadget since that feature sucks. Sounds or Feel Familiar? That is exactly what DUKKHA is, that feeling.
More dramatic representation of Dukhha is being born, aged, sick and die. Does it apparent here and now? Does this truth is timeless?
Buddha never urge anyone to become his disciples if one is unable to relate to this truth. Moreover, he also stated in Dhamma Vandana that Dhamma is Ehipassiko. Meaning that it needs to be investigated and it is not just believe because your parent / teacher / best friend told you to believe that whatever The Buddha said It is True.