No, the bishops were out zealously teaching and evangelizing. But the Faith was still developing 300 years later - look at the differences between the three major Creeds - the Apostles', the Nicene (and the further Nicene-Constantinople), and the Athenasian. The early Church didn't teach explicit Trinity - that came centuries after. And many major Fathers of the Church were lost when they could not accept Church definitions (usually in response to major heresies) such as Origen.
Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me. I am the vine, ye [are] the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. - John 15:4-5
The greatest problem that the early Church (and come to think of it, the current Church) had is just what that abiding consists of and getting people to actually abide.
For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh: That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit. For to be carnally minded [is] death; but to be spiritually minded [is] life and peace. Because the carnal mind [is] enmity against God: for it is not subject to the law of God, neither indeed can be. So then they that are in the flesh cannot please God.
But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his. – Romans 8:1-9