I’m not sure how long this expression has been around, only a few decades I’d guess. However, the Greek word agape has been viable since God expressed it to Adam and Eve. Many have tried to explain it in layman’s terms: “in spite of anything,” “what is best for another,” “unselfish” and lots of others. It is harder to learn and practice thanthe other types of love like romantic and brotherly. They most often involve a reciprocal interchange of emotions. Whereas agape love resembles 1 Corinthians 13 in that it is kind, patient, not proud, never fails. Tough love also has these qualities but usually expresses itself differently.
Tough love seems to me to be an attempt to have the recipient focus on the things that will rescue him/her from behavior that will surely damage or injure them if continued. In his sermon in Matthew 5, Jesus says difficult things such as: “turn the other cheek,” (v 39) “ love your enemy,” (v 44) and “ walk the second mile.” (v 41) He also tells us to forgive 70 X 7, (Mt 18:21-22) to love him more than family and follow him or risk not being worthy. (Mt 10:37) None of these hard commands are made in a dictatorial spirit, rather, they teach us the kind of discipline needed to share in his holiness. (Heb 12:7-10) Zacchaeus must have heard Jesus preach this before making the vow to repay those he had wronged. (Lk 19:8) Even when Jesus cleansed the temple (Mk 11:15-17) he was trying to teach the respect that the Godhead demands.
New Testament Christians today should look to scripture before we attempt to practice tough love. “Whom the Lord loves, he disciplines.” (Pr 3:12) (Heb 12:6) (Rev 3:19) He does this for our good that we may share in his holiness. (Heb 12:10) We must remember that as we attempt to teach and rescue brethren and especially outsiders, that we do it by, “teaching the truth in LOVE.” (Eph 4:15) It will involve gentleness, (1 Cor 4:21) (Eph 4:15) (1 Ti 3:13) patience, kindness, self-control, etc. (Gal 5:22-23) What we perceive as a rescue effort may be looked at as arrogance by others. We may “become their enemies by telling the truth.” (Gal 4:16) Tough love, if it is truly a form of agape, is worth any effort.