Whether you're Catholic, Protestant, Pagan, Wiccan, agnostic or atheist, I bet you feel drawn to candles and fires. It's in our ancestral shared memories, fashioned since caveman/woman days.
Fire in any way draws us in.
At its most basic, fire symbolizes warmth, protection, community. Its power is subject to the whims of user. If tended and respected, its powers can be harnessed; if not, it can cause great harm. It is one of the four basic elements: Earth, water, air & fire.
Through the flame in candles, everyone can harness the energy in fire. I never pass up an opportunity to say a wish or prayer. If you're of the nature-based and Wiccan religions, you probably say a simple spell. Either way, those flames, warmth and smoke create "magic" for everyone who takes time to shine a light in a dark place.
Why not go further and align your intent with the correct color to double the effects?
Intrigued? Find out more, start at What's Your Sign. They do a beautiful job of explaining, so I won't go into details here. Check out all the meanings and the fire symbols as depicted at
http://www.whats-your-sign.com/fire-symbols-and-meanings.html . They represent people, religions and cultures from all over the world. Quite interesting. Then pursue and experiment on your own.
For Christians, you might want to repeat my religious education's teachers invocation: "With the lighting of this candle, we invite the Holy Spirit in."
Blessings to you and yours!