Peter was explicit about his ministry of remembrance. In his second letter he said “I intend always to remind you…I think it is right, as long as I am in this body, to stir you up by way of reminder” (2 Peter 1:12-13). We forget.
Paul was eager to preach the gospel to those in Rome (1:15), the same ones who were loved by God and called to be saints (1:7). You can know, and still need to re-know. Near the end of Romans Paul wrote,
I myself am satisfied about you, my brothers, that you yourselves are full of goodness, filled with all knowledge and able to instruct one another. But on some points I have written to you very boldly by way of reminder, because of the grace given me by God to be a minister of Christ Jesus to the Gentiles in the priestly service of the gospel of God, so that the offering of the Gentiles may be acceptable, sanctified by the Holy Spirit. (Romans 15:14-16).
Paul was set apart for the gospel of God (1:1), his was priestly service of the gospel of God (15:16), and he says they knew enough about it that they could talk to about it to one another without needing to Google it. But they needed reminders.
Every week we get the reminder of the gospel, the fact of what Jesus Christ has done and the desire that God has for us in Jesus Christ: communion with Him. This is a reminder for our comfort, it is also a reminder of our calling. Jesus died and rose again as a sacrifice so that we might live for God (Romans 7:4), so that we might be sanctified and acceptable to Him.