The Lord's speech is Divine -- it had meaning to all that believe in Him. Then as now.
The whole of the NT deals with salvation, repentance, how to love the Lord and the neighbor to lead a good life according to one's religion. That's what leads to Heaven.
You quoted Corinthians. Look at the beginning of the next chapter...
3:1 And I, brethren, could not speak to you as to spiritual people but as to carnal, as to babes in Christ. 2 I fed you with milk and not with solid food; for until now you were not able to receive it, and even now you are still not able; 3 for you are still carnal. For where there are envy, strife, and divisions among you, are you not carnal and behaving like mere men? 4 For when one says, "I am of Paul," and another, "I am of Apollos," are you not carnal?
Paul is challanging those to raise their mind to the spiritual, which really anyone can do who is sincere about his faith.
That doesn't fit with what's written:
Mat 13:10 And the disciples came, and said unto him, Why speakest thou unto them in parables?
Mat 13:11 He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given.
That seems relatively clear.
The parable of the marriage supper ends with:
Mat 22:14 For many are called, but few are chosen
3:1 And I, brethren, could not speak to you as to spiritual people but as to carnal, as to babes in Christ. 2 I fed you with milk and not with solid food; for until now you were not able to receive it, and even now you are still not able; 3 for you are still carnal. For where there are envy, strife, and divisions among you, are you not carnal and behaving like mere men? 4 For when one says, "I am of Paul," and another, "I am of Apollos," are you not carnal? Paul is challenging those to raise their mind to the spiritual, which really anyone can do who is sincere about his faith.
Paul was addressing Christians. Those who had repented of their sins and had accepted the indwelling of the holy spirit. Granted they struggled with carnality, as all Christians do, but part of the purpose of the church is to help other overcome, which is what Paul was attempting to do here.
Scripture is abundantly clear that one does need the spirit of God to understand the things of God.
1Jo 3:24 And he that keepeth his commandments dwelleth in him, and he in him. And hereby we know that he abideth in us, by the Spirit which he hath given us.
But as the article points out, there are also many decievers gone out into the world, many of whom call themselves Christians:
2Co 11:13 For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ.
2Co 11:14 And no marvel; for Satan himself is transformed into an angel of light.
2Co 11:15 Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.