Communication with God. Because God is personal, all people can offer prayers. However, sinners who have not trusted Jesus Christ for their salvation remain alienated from God. So while unbelievers may pray, they do not have the basis for a rewarding fellowship with God. They have not met the conditions laid down in the Bible for effectiveness in prayer.
"Is anyone among you suffering? Let him pray. Is anyone cheerful? Let him sing psalms. Is anyone among you sick? Let him call for the elders of the church, and let them pray over him, anointing him with oil in the name of the Lord. And the prayer of faith will save the sick, and the Lord will raise him up. And if he has committed sins, he will be forgiven. Confess your trespasses to one another, and pray for one another, that you may be healed. The effective, fervent prayer of a righteous man avails much. Elijah was a man with a nature like ours, and he prayed earnestly that it would not rain; and it did not rain on the land for three years and six months. And he prayed again, and the heaven gave rain, and the earth produced its fruit." James 5:13-18 (NKJV)