Till the Conversion of the Jews
To early Christians belief was not of overwhelming importance, if one is to judge by the incidence of forced and mass conversions and conversion by conquest. Perhaps that was the cynicism of the powerful; perhaps a reflection of the hard realities of temporal allegiance; perhaps an acceptance that the rites of conversion established a reality of themselves.
To most modern Christians belief is essential to conversion, but for some denominations conversion takes place through selection by god, and is therefore irresistable.
My impression is, that in the modern polemic against religion, it is belief that is excoriated; faith escapes with its skin intact. By faith here I mean, not the sense of the corpus of belief, as in the Christian, Jewish or Muslim faith, but the word used in the sense of a personal experience. In religious discussion the it is, unhelpfully, often used simply to mean a religious belief, but there is a real distinction between belief and faith. Faith has necessarily elements of trust and adherence; there is something more reciprocal about it than with belief, which is rather more a subscription to an externality. Perhaps that is why belief draws the polemical atheist's fire, intent as he often strangely is on establishing the non-existence of any god. Notions of keeping faith, of good and bad faith, have a currency in modern non-religious thought with which it may be more enlightening to tangle.
