The reason why those chords are written like that in hymnals is because they were originally meant to be sung, not played on the piano. The top two notes would be the soprano and alto notes. The bottom two notes would be the tenor and bass notes. Now, if you play all 4 notes together, they do form a chord. They're not a broken chords per se. A broken chord is playing a chord one note at a time.
There are a few different ways you can approach this depending on what you're church wants. If you're church wants you to play the hymns as written, then you have no choice but to either get good at sight-reading or memorize the hymns.
If you're church doesn't care what you play, then you can analyze the chords of the hymns and play them how u want them. Most hymns use basic chords, so they shouldn't be too tough to analyze and figure out.
Another approach is to write in the chord symbols above the chords and just play it like a lead sheet. This is a great way to look like you're sight-reading when you're really not.
One more approach is to just read either the melody or the bass of the hymn and fill in the rest as you want. I would rather read the bass line cuz I can figure out my chords from the bass easier than from the melody.
