Keep always in mind the rule of faith which I profess and by which I bear witness that the Father and the Son and the Spirit are inseparable from each other, and then you will understand what is meant by it. Observe now that I say the Father is other [distinct], the Son is other, and the Spirit is other. This statement is wrongly understood by every uneducated or perversely disposed individual, as if it meant diversity and implied by that diversity a separation of Father, Son, and Holy Spirit
TertullianFor it is really better for us not to know a thing, because [God] has not revealed it to us, than to know it according to man’s wisdom, because he has been bold enough to assume it.
TertullianWhen we are going to enter the water ... in the presence of the congregation and under the hand of the president, we solemnly profess that we disown the devil, his pomp, and his angels. After this we are immersed three times, making a somewhat larger pledge than the Lord appointed in the Gospel. Then we are taken up [a reference to the Roman tradition of recognizing a newborn baby as a member of the family]. We first taste a mixture of milk and honey and from that day we refrain from the daily bath for a whole week.
Tertullian