stop churches emptying is congregations are dwindling

I dont know why the churches in england are empty and being sold. The Uk is 50% Christian. So why is my question as if your a christian beleive in jesus and your past sin is gone. Thats why i Believe in God and the Holy Ghost.Our chruches need reviviving not being sold our christian community is faithfull and we welcome and people to our church r you own local church the pastor will welcome you if you like singinmg its the best place to sing to God and enjoy the christiaon community , most churches have bible study ,prayer meat. and pastors go out on friday to look for druggies and kids messing about in parks to preach the bible to them to see if they can get them to go easy in their community