Christianity plays a very large role in society. There numerous Catholic Hospitals. Nearly every major city in the U.S. will have at least one. There are Catholic as well as other Christian Schools ranging from re-school through High school as well as many Catholic and non-Catholic Christian universities as well. Christian Charitable organizations do literally billions of dollars worth of social works including feeding, clothing and housing the poor. Catholic groups run adoption agencies. Catholics have one of the most well organized campaigns to overturn abortion.
Every week, in thousands upon thousands of churches throughout the western countries millions of people come together to hear the word, to pray to God, to praise Him and to seek the salvation of souls…One soul at a time. These same people go out to spread the gospel, to do works of mercy and to glorify God and build the kingdom.
Again - I must say that “Culture”, especially in the United States can be a very tricky word. For the U.S. is not one culture but many. That is the benefit and the bane of our free society.
And yes - I have no doubt that that you have met people who do not know the Bible and do not believe the Bible. I have too. But does that mean that Christianity is ineffective or that you are talking to the wrong people…

Here you will find many, many people who know the Bible and Love it - Who Love God and seek to serve Him.
These are sad numbers but what do they reflect? Do they really mean that "Christianity is ineffective?? I don’t think so. Christ said that many are called but few are chosen. He described, in the parable of the sower that, of the four types of soil the seed could land on, only one would yield fruit.
This may be. But God has given all persons free will. If they choose to behave this way… all we can do is pray for them.
I was one of those who left the faith in my late teens, spent 35 years living in sin and returned to the Church. Having done that, what do you think I believe…I believe that the Church is alive and vibrant. That it is smaller might be true. That it is dying…sorry but that is not possible. The Gates of hell will not prevail.
The Church exists and reaches out to those in need and whoa re ready to accept the good news.
Could our western societies be better? Certainly they could. But in a free, democratic, pluralistic society this must be done by winning hearts and minds and not by theocratic lawmaking.
Some societies might “look” religious but are they really?? What is simmering just below the outward signs of piety that are enforced by law that make it illegal to convert?
I do not know you background, whether you were born in America or moved here, but I can assure you that, for all the troubles that one can point to in “The West” and in Christianity in the west, the Church is not dying and indeed cannot be killed off.
Peace
James