15 if I am delayed, you will know how people ought to conduct themselves in God’s household, which is the church of the living God, the pillar and foundation of the truth.

Read 1 Timothy 3:15 Using Other Translations

But if I tarry long, that thou mayest know how thou oughtest to behave thyself in the house of God, which is the church of the living God, the pillar and ground of the truth.
if I delay, you may know how one ought to behave in the household of God, which is the church of the living God, a pillar and buttress of the truth.
so that if I am delayed, you will know how people must conduct themselves in the household of God. This is the church of the living God, which is the pillar and foundation of the truth.