Missionary broken?

[PurpleHaze34]

I watched Berlin convert with Summerian missionaries, so I created a missionary with 4 spreads via a Mosque. I send him north to Berlin, first conversion I move the needle to 6 Judaism (Sumeria) 5 Catholic (mine). I use the missionary the next two turns and it's still 6-5? is this broken or do i not understand how missionaries work?

New to Civ 6, played a lot of Civ 5.

 

[Uberfrog]

Missionaries are not good at converting citizens who already follow a different Religion. They're better early on when converting your own cities who still only follow your Pantheon, or a foreign civ who doesn't have their own religion yet.

To go on the offensive and convert a city with a different religion, it's better to use Apostles, especially if they have the right promotions.