If Jesus was the perfect and last sacrifice, why do we still make altar calls?

Why do the things that cause us to separate ourselves by denomination have little to do with what God’s Word tells us to separate ourselves from?

Why do we eat a tiny wafer, drink a sip of grape juice or wine, and call it a supper?

If Jesus told us to render to Caesar what is Caesar’s, why do we make our organizations non-profit and/or tax-free?

Why do we stand up when we sing hymns?