Verse 2 - Even as they delivered them unto us which from the beginning were eyewitnesses and ministers of the word;
Verse 3 - It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus,
One of those resources is this. Though he, himself, was not an eyewitness, he was acquainted with people who were. He had fellowship with people who fellowshipped with Jesus. Thus, he was properly set to take notes as to the person and works of Jesus. The second resource he had in his life so that he could do a fine job of declaring the Gospel were documents which he respected and made good use of. Interestingly, the documents he extracted from was not even canonized as his would be. But as was necessary, he still used them.
Now of course, this does not mean that, as far as his objective to declare the Gospel in writing was concerned, he had excuse to neglect the inspiration and guidance of the Holy Spirit. For it is clear, from the fact that his work would be ultimately canonized as scripture, that the Spirit enabled him. But as the Spirit spoke unto him directly, he also spoke unto him through others who had a direct relationship with Jesus and he spoke to him through the writings of those that were eyewitnesses to him.
So with us, what will be conducive to our doing a fine job of declaring, whether in writing or speech, the Gospel of Jesus Christ is the same two resources that Luke had. (1) We must be in fellowship with those who fellowship with Jesus Christ in spirit. Consider John and what he wrote (John 1:1-3). That which he had seen, he shows unto the recipients of his epistle, and that they might have fellowship with him. Having fellowship with him, they have fellowship with Jesus. Insomuch as we see Jesus by faith and in spirit, we will show him unto others that they might have fellowship with us. And having fellowship with us, they are having fellowship with the Father and his son Jesus. (2) Also we are to be diligent in study. In principal that means that we should be imbibing conscientiously and indiscriminately from the Holy Scriptures. But at the same time, we should not despise attending to what is in accordance to the Holy Scriptures in the written works of men either. After all, God has appointed for the Church teachers. And we should not act as if they merely speak the word of God behind pulpits, but never write it in books. Luke himself didn’t deem it harmful to read and relay what he saw in the writings of men. For in addition to being able to test the documents with one another and with what he was told vocally, he had with him his God who would lead him unto all truth in spite of whatever errors those writings might have contained. May the same God do the same for us today.

