HELP!! Upgrading gear

[Ashley]

I have been shooting with the Sony A99 for years.  I have been disappointed with the low light performance.  I photograph weddings and the low light performance is crucial

 during the ceremony...inside of a church etc.  I am left with grainy images--not professional quality... I also find myself working harder for tack sharp images.  Many of my friends have switched to the Cannon 5D mark IV and love it.  I am considering switching myself.  I would love to stay with Sony and continue using the assortment of lenses I worked so hard to acquire.  HELP!! Does anyone have a suggestion for a camera in the Sony line comparable to the performance of the Cannon 5D Mark IV?!  I have read that the Sony A9 is comparable--does anyone have any advice? Thank you!