Unless we unquestionably accept the authority of a person or group or are under total control, then some personal thought is involved in any decision to join a religion such as Christianity or one of its denominations. In simple terms when presented with a faith people “choose” to believe or “choose” not to. The “choice” that they make may be based on any number of factors. It may be based on intellect, emotion or both. In practice other factors may also have played a part. A decision may have been influenced by conditioning for instance. This would certainly explain why the majority of people follow the faith they are born into. Circumstance does play a role and this is true for people without faith too. People brought up in a secular environment are more likely to be atheist or agnostic than those brought up within a religious one.
This is a very deep area of thought. Those who believe we have no freewill at all are determinists. To them everything happens as a result of causality established by a “First Cause.” Since we do not completely think outside of environment, experience and emotion they suggest we have no “free will” at all. Our conscious perception of choice in practice is held to be subject to deeper unconscious limitations. To others our experience of consciousness and the sense of making choices leads them to hold the opposite view that we have complete and absolute freewill. They do not recognise limits at all.
In practice all branches of Christianity believe in the need for God to communicate with us in some way and that we are incapable of coming to God of ourselves. To a Catholic is by means of apostolically transmitted authority through their organisation in a number of forms. To some Protestants (such as the Christadelphians) it is only through the Bible and providence. To others it is the influence of the Holy Spirit working directly on the human heart.
A consideration of the limits of free thought in respect of Christianity is necessary for an obvious reason. Christianity has so many branches. If there was only one grouping then which was the true form would be self evident. To consider this further we need to look deeper into Christian history.