1 Peter 1:22 Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently.
”Love one another” is an oft-repeated command in Scripture, but it is also a promise: you will love one another with a pure heart fervently. When Jesus gives this ”new commandment” He also gives the desire and the power to actually do it. For the Holy Spirit comes to dwell in our hearts and actually love the brothers and sisters in Christ. We see this promise working out in churches and communities of faith everywhere.
The power comes about and the promise comes true after we have purified our souls (confessed sin and received forgiveness) in obeying the truth (believing the gospel) through the Spirit. The Spirit has brought us to faith and He renews that faith daily, with the result that we genuinely love the brothers. We love God by loving others because He first loved us. This is a beautiful promise that Christians enjoy giving and receiving.