Because Our Lord promised the Holy Spirit would be sent to His Church to teach Her all things (John 14:26). And She has been sharing Her learning with the world since the beginning at Pentacost (Acts 1).
Also, consider that Our Lord meant something. Are your children free to interpret what you mean when you instruct them or do you explain it until they see what you are meaning to convey? So it is with Christ. The Church has been given the commission to teach (2 Cor 2:17) the world because the Words of Christ are not open to personal interpretation.
"Because Our Lord promised the Holy Spirit would be sent to His Church to teach Her all things (John 14:26)."Let's take a look at John14:26 in context:
22 Judas saith unto him, not Iscariot, Lord, how is it that thou wilt manifest thyself unto us, and not unto the world?Jesus was teaching a group of people, and answering one follower's question for him and those others listening, and by extension us(as God had His inspired words recorded) for our edification.23 Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.
24 He that loveth me not keepeth not my sayings: and the word which ye hear is not mine, but the Father's which sent me.
25 These things have I spoken unto you, being yet present with you.
26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.
Jesus has a personal relationship with those that follow Him, and the message was for them (and us) Not a Church organization. For his church, yes.
It's best to not just throw out a scriptural reference and declare it means something it does not.
And She has been sharing Her learning with the world since the beginning at Pentacost (sic) (Acts 1).God shares his meaning of scripture through the Holy Spirit to followers who are born again and have that personal relationship with Him (His church)---not a "C"hurch organization.
Plus there was no Catholic church back then at Pentecost.
And your scriptural reference does not say anything about the "C"urch.
Acts 1, Jesus speaking to His followers, believers:
8 But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth.It's quite clear He was NOT giving that to any Church---referenced by you as She and Her.