Does practicing meditation mean that I will have to adopt a different religious practice?

The simple answer is no. You are more than able to enjoy TTM meditations without adopting a new or any religious practice.

In truth, meditation has been employed in just about every religion since the rise of religious practices. Prayer as practiced by the Abrahamic faiths (Christianity, Judaism, Islam), can be considered as much a meditation as the various forms of Buddhist or Hindu practices. Meditation is a discipline, in which one sets aside time to explore that which usually remains hidden from the conscious mind. It is a form of awareness training.