Building of the church
Jesus knew that he would no longer be physically in the world but he needs a way for the work to continue.
So Jesus wants those who believe in him to do the things that he was doing before, he describes this new body as the church.
He has other names for the church as well, including: "the bride of Christ".
But the church is made up from imperfect people
The problem is that the church is not made up from perfect people but from imperfect people. Although it tries hard to follow God it is not perfect. Anyone who knows anything about history will know that the church has not always been doing the right thing.
We don't believe that the church should be as divided as it is but it is made up of imperfect people and so it is.
We don't believe it is right to force people to become Christians and yet the church has been guilty of doing this in the past.
The thing is that the church knows it is not perfect and every time churches meet for worship they say how sorry they are to God for getting things wrong (known as a prayer of confession). Even the prayer that Jesus taught his disciples to say has the line "forgive us our trespasses" so Jesus must have known we would get things wrong.
The Christian church meets as a local church. Local churches are part of larger groups called denominations and these then form the worldwide church.
To be called a Christian church it needs to believe what Christians believe e.g. the creeds. This means accepting that Jesus is God.