There is Kfira [heresy] that is Emunah [belief] and there is Emunah that is Kfira.
How so?
There are people who are Kofer but are dedicated to carrying out G-dly tasks such as healing and attending to the aged and infirm or taking care of children or of searching for cures for illnesses. Or people who donate large amounts of money to Tzdaka or donate kidneys to people they might never have met. This is a form of Emunah b/c BY GOLLY where does this come from?? From a Darwinian survival of the fittest instinct? How does it help me survive if I give away my stuff or my body parts or I dedicate my life to helping others?? No! This comes from the Divine spark that dwells within every human being. [The language of Maran HaRav ztz"l ונמצא שהכופרים שהם בעלי מוסר, נובע המוסר לא מכפירתם, כי אם מהכרת א-להים הגנוזה בעומק נפשם, שהם אינם מכירים אותה.] So the person might consciously deny G-d ח"ו but their lifestyle is a contradiction to that. This doesn't absolve them from their obligation to believe in G-d but they are on the road...
Avraham Avinu was a great philosopher who found G-d and was also a great man of chesed. The bridge leading from non-belief to belief is paved with chesed. Hashem created the world with chesed and that is the road to finding Him [Maran Rosh Hayeshiva ztz"l]
Emunah that is Kfira - There are people who daven every day, say things like "Baruch Hashem" [and "oy vey"], keep a kosher home, only attend Pesach programs with hechsherim, send their children to Jewish days schools etc. etc. but they also support Toeva i.e. LGBTQ+fjr5%$#@89 and vote people into public office who support Toeva. [BTW - Joe B. is a devout Catholic who is also a devout believer in things, like the homo stuff וכל אביזרייהו, which contradict the religion he professes to follow. Ditto Barack Hussein O. A professing mosque going Muslim church going Christian who promoted agendas that contradicted his religion]. Or parents who fight tooth and nail against their children when they want to pursue further Torah study beyond what the parents expected. When there is a seeming conflict between financial success and Ruchniyus - it is a no conte$t. Or people who go into fits of almost mystical ecstasy, like on the level of Unio Mystica, over a ball going into a basket or over a wall. A person who is aware of G-d's presence cannot assign value to such frivolities. It is one thing to watch and enjoy a game. Another to believe that the score really matters. These are people who seem to be believers but this belief is contradicted by their conflicting beliefs and actions.
Another approach to Kfira that is "Hoda'a" [i.e. admission of Hashem's existence] and "Hoda'a" that is Kfira.
