What the Bible teaches about:

Assembly? Simply in the homes of Christians!
The same is applicable for todays Christians and Christians-to-be. And every new Christian can make his-/ her house available too; just as the first Christians did. In that way all cities, regions and countries will have similar Assemblies of Christians.

Biblical foundations go before Assembly and those assembled!
Romans 16:3-9
Christians are Christians because they are in [the name of] Christ by means of the baptism. And they were baptized because they have known that they can only be saved in the name of Christ; and by no other name. Consequently they are called 'Christians' (read Acts 11:26).
1Cor3:16-17 - Christians each are Temples of GOD
With a biblical foundation - Spiritual Guidance
Because- and with that new connection Christians will grow in the Fruit of the Spirit when they put the Spiritual Gifts into use according to Gods Commandments ánd the commandments of Christ (Matthew 28:19-20 - Go out, teach, preach, baptize, etc.). Without that renewed connection, consequently without the Spiritual Gifts you cannot and willnot go out as a Christians should and there will be no Fruit of the Spirit and consequently there will not be eternal life (read Matthew 25 about 'Talents and multiplying of Talents').
1Peter 4:14 - Gods Blessing upon those in the name of Christ
Church-Christianity - unbiblical foundations worldly organized
All those that claim to be saved under another name ('trinity-churchgodhead') by which they deny the Gospel with a self-fabricated church-gospel ('GOD went to Earth himself in the flesh') can- and willnot receive Gods Spirit, willnot receive Gods Spiritual Gifts and willnot receive Gods Guidance through His Spirit. Instead for all those a worldly organisation remains; an organisation that places itself above GOD, above Gods Word, above Gods Commandsments and even above all their members...
 

Church-Christianity with her unbiblical foundation and worldly organisation can- and willnot lead of GOD and willnot lead Christians to the Fruit of the Spirit. Nor will cel- or housegroup-"spin-offs" of churches be. Whatever place or shape the churches choose to organize themselves in will never be in the name of Christ nor will it lead to GOD.
Moreover: cel- and housegroups founded and/or funded/supported by the churches will have the same foundations, goals and means the churches have. The house-programs are only used by the churches to favour and strenghten the churches; they are under the old church-control and hierarchy; even when the "nasty old church" will seem far and away to the housegroup-participants... The selected housegroup-founders know that all too well, because they had to write down goals before they started; goals that usually are all about taking care of 'plugging church-studymaterials', a growing number of churchmembers and consequently more people that financially support the church and staff.
Bringing the same church-foundation, church-values, church-rites on the same broad church-ways leading to the known church-fruit the participating members and churchmembers will never be Christians nor will they be Gods Fruit in Christ.
Focus on becoming a Christian according to a biblical Foundation
Consequently - when you are churchmember or church-houseprogram (f.i. under Willow Creek, Rick Warren, etc.) you will have to leave those organisation and quit your membership. Those will be your first steps turning away from an old life without Gods Blessing and without Christ.
At the same time you will have to start with biblical foundation; by means of what the Eternal GOD has determined and founded. And that is quite different from what you may have learned in church or in your housegroup. You may need to get used to what is really biblical and leave some 'church-programming' behind, but when you are sincere and humble nothing will be impossible; instead it will appeal to your heart ánd mind more than all church-programming did!
Only after you are aware of the contents of a biblical foundation ánd believe in it ánd want to accept and apply it in your life you are ready to become a biblical Christian to be united to GOD afterwards so you can grow in Faith and the Fruit of the Spirit in service with received Spiritual Gifts.
More about being an active Christian: