Locke on Reason and Faith.
The issue of the relation between reason and faith was very important in the seventeenth century ( a period of religious and political strife in England).  Some religious positions are important with respect to Locke:

• Extreme fideism: "Credo quia impossibile." Here the idea is that the very absurdity of faith is a reason for religious belief.  Faith, in this view is epecialy worthy because it goes against reason: it's a mark of faith to belive against all evidence.
• Moderate fideism: Appeal to the authority and tradition of the Church to adjudicate religious issues in the light of reason's inability to do so.
• Enthusiasm: the belief in one's authority in religious matters because of one's infusion by the Holy Ghost.
• Deism, which accepted natural religion, but rejected of revelation and the supernatural, i.e. the Mysteries of faith (e.g., vergin birth , the resurrection from the dead, the idea that Christ is the Messiah).

Lk distinguishes between reason and faith:

• Reason is the inferring or demonstrating of certain or probable truths from the ideas gotten through experience.  With respect to reason, statements can be divided into three categories:
1. statements in accordance with reason, i.e., truths arrivable at by reason.
2. statements contrary to reason, i.e.,  inconsistent with what we know to be true, e.g., more than one God; trinity (probably)
3. statements above reason, i.e., consistent with what we know to be true, but unarrivable by reason. ex. resurrection; divinity of Christ; virgin birth.
• Faith is the acceptance of revelation.  For Lk:
1. the proper realm of faith is statements above reason. Hence faith goes beyond reason but cannot contradict it.
2. One must have reasons for believing that alleged revelation is true revelation. Ex. immoral precepts disqualify, since reason tells us God is good. Hence, importance of the rational study of the sources of revelation: textual exegesis of Scriptures

NOTE: So, Locke accepts that if P is divinely revealed we ought to accept it; however, he wants proof that P is divinely revealed.
3. Reason demands the rejection of credo quia impossibile and of enthusiasm.

NOTE: Since Lk. accepts revelation, he isn't a deist.

Belief and toleration: belief doesn't directly depend on our will, although we can affect it by inquiring on a subject matter or not. (IV, 20, 16)  This provides the basis for his claim in the Letter on Toleration, that therefore belief cannot be forced, and consequently the State should exercise religious toleration (atheists and Catholics excluded, however).