Is faith in Jesus Christ the only way to heaven?
If you are a Christian, then absolutely. But there are plenty of Jews, Muslims, Buddhists, Hindus, Shintoists, pagans, and others who believe their faith will get them into Heaven. John 3:16 aside, faith in Jesus Christ is but one path to the Divine. There are many paths, each equally valid to those that follow them. If faith in Jesus, Allah, Shiva, Buddha, Jehovah, Yahweh, or nothing at all is what connects you with the Divine, then more power to you.
I don’t subscribe to the idea that Heaven is an exclusive club where admittance is dependent upon whom and how we worship. Reaching Heaven, Nirvana, Enlightenment, or whatever you wish to call it, is a journey and we must each find our own path to follow. Some paths lead us toward our destination while others lead us away. Whatever path we are following, we can always chose another and another and another. Eventually, we will get there.