The question was asked about a congregation raising money from the community at large to build a bigger building. Specifically, if such a practice is biblical or not. For something to be “biblical”, it has to be found in the Bible. That’s what “biblical” means! So, if we could find somewhere in the Bible where the work of the church was funded by raising money from the general public, it would be biblical. If we cannot find anything in the Bible allowing for such a practice, it would not be biblical.
Since the question has to do with building a church building, let me first respond to those who claim even having a building is unscriptural. There are some who claim that the purchase of property for church assemblies is unbiblical because you don’t find any such buildings in the New Testament. However, there are examples of the church meeting in homes. A specific example would be the church at Colosse meeting in Philemon’s home (cf. Philemon 1:1-2, 10-12; Colossians 4:9). So, Philemon – a member of the church in Colosse – used his personally owned property to facilitate the assembly of the saints. He was authorized to do so by the command for the saints to assemble on the first day of the week (cf. Acts 20:7; 1 Corinthians 16:1, 2; 11:18, 20, 33). If it is acceptable for one Christian to own property for the assembly of the church then, certainly, Christians can collectively choose to own property for the assembly of the church.
The passages cited above also show that the first day of the week collection is for the work of the church. Paul said to “lay something aside…that there be no collections when I come” (1 Corinthians 16:2). Paul’s command was for them to have a treasury prepared to provide for the need he was raising support to meet. That is, to relieve the saints of Jerusalem suffering under a famine (cf. Acts 11:28, 29). The work of benevolence would be provided for by the church gathering the funds from a weekly collection on the first day of each week. In 2 Corinthians 8:3-5, Paul shows that this is also an act of worship in expressing our love and devotion to God. The principles here are clear! The church meets the needs of her work – evangelism, edification, and benevolence – by means of a free-will offering made by the saints in their first day of the week worship assembly. The collection is not to be on an “as needed” basis but is to be gathered into a treasury to meet the needs as they arise.
For the church to collectively provide a building for their assembly would be part of the work of edification. Therefore, it would be an authorized expense of the church for the work of the church. Just as the church funds it’s evangelistic outreach and the work of benevolence through the weekly collection, so too is that how the work of edification is to be funded.
There is nowhere I could go in the New Testament for an example of the church taking money from outside the church to do the work of the church. If I can’t find any such example in the New Testament then such a practice would not be biblical.