Some have accused Baptists of denying the gospel because they insist that baptism (immersion) must precede any participation in the Lord's Supper. John Stott, for example, argues that Galatians 2:11-14 teaches us to welcome all believers to the Lord's Supper, regardless of what mode of baptism they received. Stott says that when churches make immersion a prerequisite of communion at the Lord's Supper, they are denying the gospel.
However, there are two problems with Stott's notion.
First, it proves too much. If we were to admit people to the Lord's Supper on the basis of faith alone, then it would be wrong to insist that baptism itself is prerequisite. Surely Stott doesn't believe that. A simple profession of faith alone in Christ alone would have to be sufficient, and no manner of church polity could govern the Lord's Supper.
Second, Galatians 2:11 does not say that Peter refused to take the Lord's Supper with the Gentiles. Rather, it says that he drew back from dining with the Gentiles in a fellowship meal. It also says that he separated himself from them. Peter's sin was that he refused Christian fellowship to genuine believers. The picture here is not that Peter refused to partake of the Lord's Supper with the Gentiles but that he wouldn't eat with them at church fellowships. It is entirely possible that Peter did participate in the ordinance/rite of the Lord's Supper with the Gentiles while still refusing to dine with them at fellowship meals, though we are not told what actually took place.
Baptists are happy to dine with brothers and sisters who have not been baptized, to fellowship with them, and to enjoy their company as fellow believers. I would gladly sit down for dinner with Martin Luther, John Calvin, and Jonathan Edwards! They are beloved brothers in Christ, and I have no doubt whatsoever that they would greatly edify me. I would certainly not keep back from them or separate from Christian fellowship with them. The universal church is a marvelous thing and we can benefit from Christians across all Christian denominations and churches.
However, an unbaptized person should not be permitted to join the church or invited to take the Lord's Supper because the pattern of polity revealed in the NT is that baptism precedes membership and Communion. We can love a person and have fellowship with him even while insisting that the NT pattern of polity be followed.