As we saw in our previous answer, the sinner’s prayer is a prayer that involves praying the facts of the gospel out loud. But some have taken this error a step further and added things to the prayer that aren’t in the gospel. Things like asking Jesus into your heart to be saved.
Now, once you are saved, it is true of you that “Jesus Christ is in you” (2 Cor. 13:5), and Paul gives away the location of Christ’s home within you when he prayed “that Christ may dwell in your hearts by faith” (Eph. 3:17). The problem with asking Christ to come into your heart is that the Bible never tells sinners to ask Him into their hearts. And the reason it never tells them to do so is that when a sinner believes the gospel, the Lord enters his heart whether he asks Him to or not. So asking Jesus into your heart to be saved confuses the means of salvation with the result of salvation.
The entrance of Christ into your heart when you believe is one of many results of salvation you obtain the moment you believe without having to ask for them. These include things like the forgiveness of sins, redemption, justification and positional sanctification. You don’t have to ask for any of these things; you receive them the moment you trust Christ as your Savior. This is the ultimate in bundling! And the blessing of having Christ enter your heart without having to ask Him is part of that blessed bundle. source