According to spurgeon they teach only orthodox truths from the beginning, I am not sure all can be found in the beginning that they held to as standards but this one teaching on the Trinity was fundamental to the early church and Spurgeon stood for this "truth" also see these quotes by Spurgeon:
"It needs the Trinity to make a Christian, it needs the Trinity to cheer a Christian, it needs the Trinity to complete a Christian, it needs the Trinity to create in a Christian the hope of glory. I always like these passages which bring us so near to the Trinity. Let us pause a while and adore: ‘Glory be unto the Father, and to the Son, and to the Holy Ghost: as it was in the beginning, is now, and ever shall be, world without end! Amen.’ It is most sweet to be called upon to offer special worship unto the one God in the Trinity of his divine Persons, and to feel your heart readily inclined thereto, as we do at this hour”
"When thou sayest, ‘Saviour,’ remember there is a Trinity in that word ”” the Father, the Son, and the Holy Ghost, this Saviour being three persons under one name. Thou canst not be saved by the Son without the Father, nor by the Father without the Son, nor by Father and Son without the Spirit. But as they are one in creation, so are they one in salvation working together in one God for our salvation, and unto that God be glory everlasting, world without end, Amen.”
"Learn, then, O believer ,to love all the persons of the Divine Trinity alike. Remember that salvation is no more the work of one than of the other. They all three agree in one; and as in the creation they all said, ‘Let us make man;’ so in salvation they all say, ‘Let us save man;’ and each of them does so much of it that it is truly the work of each and undividedly the work of all”
"Get a clear idea, then, of the Trinity in Unity. Do not reason about it; do not try to understand it: remember, it is not your duty to comprehend, but to apprehend such truths as these: you are to believe, rather than to reason. One God in the Trinity of his persons let us know and worship; for remember that, those who do not now this, very seldom know much else about divine things; for a very remarkable fact it is, that when the doctrine of the Trinity is given up, the other doctrines of the evangelical system are pretty sure to be cast to the winds. This doctrine of the Trinity in Unity seems to be the place of standing or falling with public teachers and private believers.”
