Why to spread religion in the first place?
This can help you to gain friends and allies. Together you can rally and wipe out your religous foes, or force them to believe in your religion.
Or just having a good reason for going to war
Finally you can build UN and win a diplomatic victory.
Always seek peace. This will ensure open borders and your converters can do their job.
Starting your civ:
So you pick a good spot for your first city, the capital. It should be a place with trees. But dont chop all trees as soon as possible.
Let your capital reach 3000 inhabitants before building a worker, discover bronze working so u can get production from trees.
Build a settler with your capital. When you have builded the settler build the oracle.
after that aim to discover priesthood, i think it is, so you can build the Oracle. The Oracle gives you one free tech.
If your timing is right you can choose a tech that will give you a religion when you have finished the oracle.
When you have builded the Oracle you should have 2 cities. In the smaller city you will found the religion and it will become a holy city, and it will generate a converter. Now you can convert your capital.
The oracle will give you a prophet after a while, meanwhile spread your religion to other civs that doesnt have a religion. this can give you strong friends.
When you get the prophet take it to your smaller city and use the prophet to make the shrine.
-shrine: for example if it was christianity then the shrine would be church of nativity.
Christianity is strong because you also get theocrazy.. this means only your religion can spread in your cities. change to theocrazy when you can.
You cant win anything by converting all your enemies cities to your religion other than getting a diplomatic victory. But its cool
One thing though: you can get a lot of money when you have builded the shrine.
This can help you to gain friends and allies. Together you can rally and wipe out your religous foes, or force them to believe in your religion.
Or just having a good reason for going to war

Finally you can build UN and win a diplomatic victory.
Always seek peace. This will ensure open borders and your converters can do their job.
Starting your civ:
So you pick a good spot for your first city, the capital. It should be a place with trees. But dont chop all trees as soon as possible.
Let your capital reach 3000 inhabitants before building a worker, discover bronze working so u can get production from trees.
Build a settler with your capital. When you have builded the settler build the oracle.
after that aim to discover priesthood, i think it is, so you can build the Oracle. The Oracle gives you one free tech.
If your timing is right you can choose a tech that will give you a religion when you have finished the oracle.
When you have builded the Oracle you should have 2 cities. In the smaller city you will found the religion and it will become a holy city, and it will generate a converter. Now you can convert your capital.
The oracle will give you a prophet after a while, meanwhile spread your religion to other civs that doesnt have a religion. this can give you strong friends.
When you get the prophet take it to your smaller city and use the prophet to make the shrine.
-shrine: for example if it was christianity then the shrine would be church of nativity.
Christianity is strong because you also get theocrazy.. this means only your religion can spread in your cities. change to theocrazy when you can.
You cant win anything by converting all your enemies cities to your religion other than getting a diplomatic victory. But its cool

One thing though: you can get a lot of money when you have builded the shrine.