If the Sunday service and sermon aim primarily at evangelism, it will bore the saints. If they aim primarily at education, they’ll bore and confuse unbelievers. If they aim at praising the God who saves by grace they’ll both instruct insiders and challenge outsiders.
If God's free grace given to us in Jesus isn't the focus of a worship service (the singing, the preaching, etc.), then "worship" is merely another worthless religious self-delusion.