As one of those conservative Christians, I would point out a few things (apologies if this has already been touched on since I haven't read the entire thread yet):
1. The passage you quote has a context that needs to be borne in mind. What happens immediately after that description you quote from Acts 4? Acts 5 has the story of Ananias and Sapphira who were killed (by God) for their deceitful behavior. The critical verse here is :
Whiles it remained, was it not thine own? and after it was sold, was it not in thine own power? why hast thou conceived this thing in thine heart? thou hast not lied unto men, but unto God.
Acts 5:4
The church did, in no way, enforce the (re)distribution of wealth, but they were found giving all they had only under the guidance of the Holy Spirit. In other words, this was a community of believers - not an economic system in which everyone was taking part. The point is twofold :
i) Participation in this was voluntary. This is comparable (though maybe not an absolutely direct comparison) to charitable organizations in the capitalistic economy. The church was modelling that in its ideal operation. People give, others distribute, no one makes money (thus, non-profit).
ii) To extend that to an economic model for the whole world (as history has shown amply just in the last century or so) is catastrophic as it results in the worst tyranny. Fallen men operating a system meant for regenerate men (I speak as a Christian to other Christians) is just man's way of trying to foist his own idea of utopia upon the rest of the world. It doesn't work. There is no system of itself that is perfect, but when one assumes man is basically good (as socialism/communism does) and proceeds apace - the safeguards that a system which assumes man is basically self-seeking and bad (at heart) includes are done away with and fallen men are given free reign to impose their own will on everyone else. Communism as an ideal (isolated from its Marxist atheistic moorings) is good. Man is not.
The thing that scripture shows from early on is that God establishes the idea of private property. Thou shalt not steal pretty clearly sets that mandate. And as a civil fundamental (how many Communist rulers ever gave all they had for the cause and benefit of their fellow man?) it is foundational and absolutely necessary to prevent chaos - simply because man is selfish.
2. Jesus Himself never endorsed such a thing but made it clear that there would ALWAYS be inequality, and so to try and make into temporal reality that which is only ever shown to be realized after a spiritual transformation (i.e. in saved individuals) is to deny that which Jesus said :
For ye have the poor with you always, and whensoever ye will ye may do them good: but me ye have not always.
Mark 14:7
In context, a woman had spent a huge amount of money on perfume to anoint Jesus' feet with. It was rather extravagant (in a day where the poor were VERY poor) and that was Jesus' response to the disiciples' complaint that the money was wasted when it might be given to the poor. Thinking again of the Acts 4 model, Jesus should have agreed with this - but not only did she not give the money to the disciples, she didn't give it to the poor! She exercised her freedom to do what she wanted to do with what was hers. And John's gospel tells us that it was really Judas Iscariot who complained (John 12:4-5)! Not much has changed. The ones who cry the loudest (in high places, at least) about inequality and giving to the poor are often the ones who have hidden agendas.
3. Finally, I note that this has been attempted in some way in the early 20th century. It was called the social gospel and brought social injustice to the forefront as a primary motivation to preaching the gospel. Problem is, the gospel got all tangled up in physical prosperity and temporal motivation dominated what was supposed to be spiritual (God wants you not to be poor became God wants you to be rich...God wants you to live a life of spiritual victory became God wants you to live a life of temporal success) and now that has become the prosperity gospel on steroids. When men are promised trials and poverty and all that the world can throw at them and the gospel still wins out, those who are saved are not trapped by the lust of the eyes, the lust of the flesh or the pride of life. The social gospel obscured that and we are at the point now where it has become (in some circles) ALL about what you want. In other circles, the gospel has all but shriveled up and social causes have become the main (only) motivation. And those are often the ones promoting some sort of Christian Socialism. And again...I refer you back to my point 1.
