Cornelius and his household received the gift of the Holy Ghost without being baptized, in Acts 10.
Isn't that proof enough for you that baptism doesn't automatically warrant the gift of the Holy Ghost?
Here is the text..."But when they believed Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women.
13 Then Simon himself believed also: and when he was baptized, he continued with Philip, and wondered, beholding the miracles and signs which were done.
14 Now when the apostles which were at Jerusalem heard that Samaria had received the word of God, they sent unto them Peter and John:
15 Who, when they were come down, prayed for them, that they might receive the Holy Ghost:
16 (For as yet he was fallen upon none of them: only they were baptized in the name of the Lord Jesus.)" (Acts 8:12-16)
There are two distinctive ways in which the Holy Spirit acts and these are often confused, not the least because the same phrases are used in scripture regarding them. These two ways are referred to by Long & McMurray in their book
Receiving The Power as ‘the Spirit
within’ and ‘the Spirit
upon’. These relate to the internal work of the Spirit for salvation - sanctifying gifts, and the external work for ministry - charismatic gifts.
Long & McMurray use the imagery of a tree where, in the external work, the Spirit gives gifts like those on a Christmas tree, which can be added or removed. They are given for ministry and for the building up of the Church. The internal work is more like the sap permeating the tree giving it life and producing fruit that comes from within. Thus the internal work helps us grow in holiness and spiritual fruitfulness.
When scripture uses the phrase “receive the Holy Spirit” (or similar) it may be using it to refer to either “the Spirit
within” or the “Spirit
upon”. Some discernment is needed and sometimes the text is not clear. One test is whether there is some manifestation of “the Spirit upon”.
The Spirit Upon
In Acts, Luke seems to use the term exclusively for “the Spirit
upon”. At Pentecost the Holy Spirit, in the form of tongues of fire, comes to rest on those in the Upper Room and they all begin to speak in tongues (manifestation) (Acts 2:1-4)
In Acts 10 the Holy Spirit
falls on Cornelius and his household and they began to speak in tongues (manifestation). Peter says "Can any one forbid water for baptizing these people who have
received the Holy Spirit just as we have?" (vs 47) – referring to Pentecost. This is “the Spirit
upon”.
In Acts 8 Phillip has been baptizing in Samaria. Peter and John are sent to lay hands on those baptized and prayed for them “that they might
receive the Holy Spirit; for it had not yet
fallen on any of them, but they had only been baptized in the name of the Lord Jesus. Then they laid their hands on them and they
received the Holy Spirit.” (Acts 8:15-17). Though no particular manifestation is reported there clearly was one because Simon the magician wanted to have the same power saying "Give me also this power, that any one on whom I lay my hands may
receive the Holy Spirit." (Vs 19)
The Spirit Within
Paul himself, in his writings, seems to use receiving the Holy Spirit in the sense of “the Spirit within” (for character and salvation)
“For you did not receive the spirit of slavery to fall back into fear, but you have received the spirit of sonship. When we cry, "Abba! Father!" it is the Spirit himself bearing witness with our spirit that we are children of God” (Rom 8:15-16)
“Now we have received not the spirit of the world, but the Spirit which is from God, that we might understand the gifts bestowed on us by God.” (1Cor 2:12)
“Do you not know that your body is a temple of the Holy Spirit within you, which you have from God?” (1Cor 6:19)
We receive the Holy Spirit
within at baptism.
In the example of Cornelius they received the Holy Spirit
upon and this was evidenced by their speaking in tongues. But they still needed to be baptised to receive the Holy Spirit
within.
In Acts 8 as I said above Peter and John prayed over them because the Holy Spirit had not yet
fallen on any of them. This was the Spirit
upon. They had already received the Holy Spirit
within at baptism.