The reference to earnest love had appeared earlier in 1 Peter 1:22 (see on that passage). Now that Christ’s return could occur at any time (and hence believers be delivered from suffering), the pressure is on to keep holding on to each other through attitudes and deeds of sincere love. This love is meant to be intense as well as persistent.
8 Above all, keep loving one another earnestly, since love covers a multitude of sins.