The believers at Pentecost “were all filled with the Holy Spirit” (Acts 2:4), but the Apostle Paul never anywhere says that all the members of the Body of Christ are filled with the Holy Spirit. It is surely clear from the record that the Corinthians and the Galatians, for example, were not filled with the Spirit, for Paul’s letters to these churches contain much of rebuke and correction. And it is also evident that believers today are not — even the best of them — wholly filled with the Spirit. The filling with the Spirit is now a goal, an attainment, which the Apostle, by inspiration, sets before us. We are not all filled with the Spirit as a matter of fact, as were the Pentecostal believers. While the Spirit does indeed dwell within us by God’s grace, we must daily appropriate His help by faith.
Hence the Apostle now exhorts believers: “Be filled with the Spirit” (Eph. 5:18) just as he exhorts them and prays for them, that they may be “filled with the fruits of righteousness” (Phil. 1:11); “filled with the knowledge of His will” (Col. 1:9); “filled with all the fulness of God” (Eph. 3:19), yet none of us have been completely filled with any of these.
The reason why we are not automatically filled with the Spirit is another matter, but let the reader not fail to first recognize the fact that while the believers gathered in the upper room at Pentecost were all filled with the Spirit, the believers under Paul, and since that time, have not all been filled with the Spirit. Moreover, while it is distinctly stated, again and again, that the Pentecostal believers were, or were to be, baptized with the Spirit, not once does Paul in his epistles teach that members of the Body of Christ are baptized with or in the Spirit. Instead he exhorts them to appropriate God’s grace by faith so that they may be filled with the Spirit. source