There is a parable about the solitary Christian being like a single glowing coal removed from a fire which becomes dark and cold until replaced in the fire: the single Christian being regarded non-viable and his faith doomed unless or until he is warmed by the community of a church.
But this parable is only a valid analogy when the church is indeed a fire of faith and truth; when the church is cold, dark, dead - then there can be no sustaining of faith.
Indeed matters are much worse than that in most self-identified Christian churches - since the faithful coals are being gathered and extinguished and used for some other (and unChristian) purpose. As when the church leaders chill the church fires, and the resulting dead coals are used to surface a path leading to some Leftist political goal (African economic aid, climate-environmentalism, supporting socialism, encouraging mass immigration, extending the scope of the sexual revolution... whatever).
In modern conditions, in most places, for most Christians, most of the time - there is no social-fire of faith and truth which can warm and sustain them.
What then? Well, a great enemy of faith is incoherence; someone identifies and Christian, tries to be Christian - but some aspect of their belief system is at war with this and they end-up being incrementally corrupted; indeed may end-up being inverted and (overall, on average) anti-Christian.
What are the enemies of faith? Dishonesty is the most significant, neglected enemy of faith - many people, especially among the most educated segment of the population, have jobs that depend on positively asserting untruth, distorting and concealing the truth as they best understand it... This is cumulatively-lethal to Christianity unless it is acknowledged and repented - which seldom happens (instead people excuse themselves and rationalise the necessity of lying).
Another example is allowing left wing politics to underpin Christianity, instead of the other way around - to take politics more seriously than religion. Examples are legion - but one would be that the Church of England allows its clergy to deny the divinity of Christ/ the virgin birth/ the resurrection/ and be atheists and communists (which is an intrinsically atheist ideology) and to advocate sex not-between a husband and wife --- but CofE priests are not permitted to be members of (legal, semi-mainstream, moderate) English or British nationalist political parties. This demonstrates that the CofE leadership is rooted-in leftist politics, and not Christianity. Organisationally, it is not a true church, but a fake church.
(The same applies to most other mainstream denominations as much or more; I use the CofE as my general example because I know it best and am officially a member. And despite that the specific church I support is on-the-whole faithful and alive like a fire, and does sustain faith for several hundred people, in the style of the parable. Yet there are significant incoherences of belief and practise, and these do weaken and dissipate members.)
At the very least, to be a church member and a serious Christian requires an attitude of extreme suspicion, of mistrust - since otherwise one will likely be led-astray.
I would therefore revise the analogy of the coal and the fire to apply to individuals and their core beliefs; instead of individuals in their social organisations. I mean, if a specific Christian belief is a glowing coal, then it needs to be surrounded by other glowing coals of Christian belief in order that it does not fade and die.
Christians therefore need to work towards coherence in their beliefs, and to discover and change any beliefs which tend to isolate and chill faith. And each person can only do this for himself or herself - there may be nobody trustworthy such that it can be second-hand. Other people can help with pointers - but most other people are likely to do more harm than good.
In sum, for Christian faith to be strong, resilient and personally-sustaining; we now 'always' need to validate all important aspects of faith for ourselves, by direct knowledge and revelation - through prayer, meditation, contemplation and whatever method works for an individual.
And only by such validation can our faith become coherent and cross-linked and robust-enough to survive in a deviously-hostile world.