Well, my FRiend, it is you who "connected the dots" and claimed the kindness of the children was the True Church of God on display...not Jesus. And, no, Jesus and Paul do not contradict one another. But, Jesus was principally teaching the Jews the Law and the Prophets, the Old Covenant. Paul was teaching Gentile believers (likely you, and absolutely me) what it means to be grafted into the New Covenant. And, according to Paul, the New Covenant was not inaugurated until His blood was shed. Thus, much of M,M,L & John are the Old Covenant that you may be trying to live...but failing.
But, Jesus was principally teaching the Jews the Law and the Prophets, the Old Covenant.
Mathew 23:33
You serpents, you generation of vipers, how can you escape the damnation of hell?
In the verses below he was talking to his disciples, many of them no doubt who were preaching the Gospel before Paul was even converted.
And of course we know that is what his apostles were doing in acts.
John 14
15 If you love me, keep my commandments.
Mathew 24
14 And this gospel of the kingdom, shall be preached in the whole world, for a testimony to all nations, and then shall the consummation come.
Who`s Gospel was Jesus talking about? i don`t think it was Pauls.
Mathew 16
28 Amen I say to you, there are some of them that stand here, that shall not taste death, till they see the Son of man coming in his kingdom.
The same kingdom he referred to in 24:14
Matthew 24
35 Heaven and earth shall pass away, but my words shall not pass away.
I think we better take what Jesus said seriously, they are the works of love.