I agree with WBY. Marlin, your website refers to 1 Corinthians 2 to prove that Christians also employed secret knowledge:
1 Cor. 2:6-7
We do, however, speak a message of wisdom among the mature, but not the wisdom of this age or of the rulers of this age, who are coming to nothing. No, we speak of God's secret wisdom, a wisdom that has been hidden and that God destined for our glory before time began.
While there is without doubt some teachings that require a more mature faith to understand or accept (the "milk" Paul talks of are the things the LDS talk about most: "instruction about baptisms, the laying on of hands, the resurrection of the dead, and eternal judgment" (Hebrews 6:2)), that is not to say it requires a more mature faith to
know. The advanced material, the "solid food" is described as "teaching about righteousness" and "distinguishing good from evil". That understanding is there to be accessed from the moment Christ is believed. And Paul confirms this in Corinthians:
(v.9-10)
However, as it is written:
"No eye has seen,
no ear has heard,
no mind has conceived
what God has prepared for those who love him" — but God has revealed it to us by his Spirit.
When he speaks here of "spiritual truths in spiritual words" (v.13) he refers to the gospel of Christ, who as I've said before,
is the mystery of God (Col. 2:2):
Romans 16: 25-26
Now to him who is able to establish you by my gospel and the proclamation of Jesus Christ, according to the revelation of the mystery hidden for long ages past, but now revealed and made known through the prophetic writings by the command of the eternal God, so that all nations might believe and obey him...
Eph.3:2-6 Surely you have heard about the administration of God's grace that was given to me for you, that is, the mystery made known to me by revelation, as I have already written briefly. In reading this, then, you will be able to understand my insight into the mystery of Christ, which was not made known to men in other generations as it has now been revealed by the Spirit to God's holy apostles and prophets. This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus.
And just in case it is still unclear whether there is any other mystery involved, any other secret knowledge that absolutely
needs to be known, he adds this:
Eph. 3:8-12
Although I am less than the least of all God's people, this grace was given me: to preach to the Gentiles the unsearchable riches of Christ, and to make plain to everyone the administration of this mystery, which for ages past was kept hidden in God, who created all things. His intent was that now, through the church, the manifold wisdom of God should be made known to the rulers and authorities in the heavenly realms, according to his eternal purpose which he accomplished in Christ Jesus our Lord. In him and through faith in him we may approach God with freedom and confidence.
And as we know, even with such a great commission, Paul rarely baptized anyone (1 Cor. 1:14-17), "For Christ did not send me to baptize, but to preach the gospel — not with words of human wisdom, lest the cross of Christ be emptied of its power". Baptism is for those who already believe the message, and therefore are already saved by its power.
To make this knowledge known — to "administer" the mystery — requires no authority but Christ's commission, and no other mediator is necessary to accomplish it. "In him and through faith in him we may approach God with freedom and confidence."